2018 - SW Simulation - Plastic [PDF]

Zitiervorschau

SOLIDWORKS Plastics

ENG

SYSPRICE - REVENDA SOLIDWORKS +55 112165.6900 www.sysprice.com.br

SOLIDWORKS SOLIDWORKS Plastics

Dassault Systèmes SolidWorks Corporation 175 Wyman Street Waltham, MA 02451 U.S.A.

© 1995-2017, Dassault Systemes SolidWorks Corporation, a Dassault Systèmes SE company, 175 Wyman Street, Waltham, Mass. 02451 USA. All Rights Reserved. The information and the software discussed in this document are subject to change without notice and are not commitments by Dassault Systemes SolidWorks Corporation (DS SolidWorks). No material may be reproduced or transmitted in any form or by any means, electronically or manually, for any purpose without the express written permission of DS SolidWorks. The software discussed in this document is furnished under a license and may be used or copied only in accordance with the terms of the license. All warranties given by DS SolidWorks as to the software and documentation are set forth in the license agreement, and nothing stated in, or implied by, this document or its contents shall be considered or deemed a modification or amendment of any terms, including warranties, in the license agreement. Patent Notices SOLIDWORKS® 3D mechanical CAD and/or Simulation software is protected by U.S. Patents 6,611,725; 6,844,877; 6,898,560; 6,906,712; 7,079,990; 7,477,262; 7,558,705; 7,571,079; 7,590,497; 7,643,027; 7,672,822; 7,688,318; 7,694,238; 7,853,940; 8,305,376; 8,581,902; 8,817,028; 8,910,078; 9,129,083; 9,153,072; 9,262,863; 9,465,894; 9,646,412 and foreign patents, (e.g., EP 1,116,190 B1 and JP 3,517,643). eDrawings® software is protected by U.S. Patent 7,184,044; U.S. Patent 7,502,027; and Canadian Patent 2,318,706. U.S. and foreign patents pending. Trademarks and Product Names for SOLIDWORKS Products and Services SOLIDWORKS, 3D ContentCentral, 3D PartStream.NET, eDrawings, and the eDrawings logo are registered trademarks and FeatureManager is a jointly owned registered trademark of DS SolidWorks. CircuitWorks, FloXpress, PhotoView 360, and TolAnalyst are trademarks of DS SolidWorks. FeatureWorks is a registered trademark of HCL Technologies Ltd. SOLIDWORKS 2018, SOLIDWORKS Standard, SOLIDWORKS Professional, SOLIDWORKS Premium, SOLIDWORKS PDM Professional, SOLIDWORKS PDM Standard, SOLIDWORKS Simulation Standard, SOLIDWORKS Simulation Professional, SOLIDWORKS Simulation Premium, SOLIDWORKS Flow Simulation, eDrawings Viewer, eDrawings Professional, SOLIDWORKS Sustainability, SOLIDWORKS Plastics, SOLIDWORKS Electrical Schematic Standard, SOLIDWORKS Electrical Schematic Professional, SOLIDWORKS Electrical 3D, SOLIDWORKS Electrical Professional, CircuitWorks, SOLIDWORKS Composer, SOLIDWORKS Inspection, SOLIDWORKS MBD, SOLIDWORKS PCB powered by Altium, SOLIDWORKS PCB Connector powered by Altium, and SOLIDWORKS Visualization are product names of DS SolidWorks. Other brand or product names are trademarks or registered trademarks of their respective holders. COMMERCIAL COMPUTER SOFTWARE - PROPRIETARY The Software is a "commercial item" as that term is defined at 48 C.F.R. 2.101 (OCT 1995), consisting of "commercial computer software" and "commercial software documentation" as such terms are used in 48 C.F.R. 12.212 (SEPT 1995) and is provided to the U.S. Government (a) for acquisition by or on behalf of civilian agencies, consistent with the policy set forth in 48 C.F.R. 12.212; or (b) for acquisition by or on behalf of units of the Department of Defense, consistent with the policies set forth in 48 C.F.R. 227.7202-1 (JUN 1995) and 227.7202-4 (JUN 1995) In the event that you receive a request from any agency of the U.S. Government to provide Software with rights beyond those set forth above, you will notify DS SolidWorks of the scope of the request and DS SolidWorks will have five (5) business days to, in its sole discretion, accept or reject such request. Contractor/ Manufacturer: Dassault Systemes SolidWorks Corporation, 175 Wyman Street, Waltham, Massachusetts 02451 USA.

Copyright Notices for SOLIDWORKS Standard, Premium, Professional, and Education Products Portions of this software © 1986-2017 Siemens Product Lifecycle Management Software Inc. All rights reserved. This work contains the following software owned by Siemens Industry Software Limited: D-Cubed® 2D DCM © 2017. Siemens Industry Software Limited. All Rights Reserved. D-Cubed® 3D DCM © 2017. Siemens Industry Software Limited. All Rights Reserved. D-Cubed® PGM © 2017. Siemens Industry Software Limited. All Rights Reserved. D-Cubed® CDM © 2017. Siemens Industry Software Limited. All Rights Reserved. D-Cubed® AEM © 2017. Siemens Industry Software Limited. All Rights Reserved. Portions of this software © 1998-2017 HCL Technologies Ltd. Portions of this software incorporate PhysX™ by NVIDIA 20062010. Portions of this software © 2001-2017 Luxology, LLC. All rights reserved, patents pending. Portions of this software © 2007-2017 DriveWorks Ltd. © 2011, Microsoft Corporation. All rights reserved. Includes Adobe® PDF Library technology Copyright 1984-2016 Adobe Systems Inc. and its licensors. All rights reserved. Protected by U.S. Patents.5,929,866; 5,943,063; 6,289,364; 6,563,502; 6,639,593; 6,754,382; Patents Pending. Adobe, the Adobe logo, Acrobat, the Adobe PDF logo, Distiller and Reader are registered trademarks or trademarks of Adobe Systems Inc. in the U.S. and other countries. For more DS SolidWorks copyright information, see Help > About SOLIDWORKS. Copyright Notices for SOLIDWORKS Simulation Products Portions of this software © 2008 Solversoft Corporation. PCGLSS © 1992-2017 Computational Applications and System Integration, Inc. All rights reserved. Copyright Notices for SOLIDWORKS PDM Professional Product Outside In® Viewer Technology, © 1992-2012 Oracle © 2011, Microsoft Corporation. All rights reserved. Copyright Notices for eDrawings Products Portions of this software © 2000-2014 Tech Soft 3D. Portions of this software © 1995-1998 Jean-Loup Gailly and Mark Adler. Portions of this software © 1998-2001 3Dconnexion. Portions of this software © 1998-2014 Open Design Alliance. All rights reserved. Portions of this software © 1995-2012 Spatial Corporation. The eDrawings® for Windows® software is based in part on the work of the Independent JPEG Group. Portions of eDrawings® for iPad® copyright © 1996-1999 Silicon Graphics Systems, Inc. Portions of eDrawings® for iPad® copyright © 2003 - 2005 Apple Computer Inc. Copyright Notices for SOLIDWORKS PCB Products Portions of this software © 2017 Altium Limited. Document Number: PMT1839-ENG

Contents

Introduction About This Course . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Course Design Philosophy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Using this Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 About the Training Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Conventions Used in this Book . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Use of Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 More SOLIDWORKS Training Resources. . . . . . . . . . . . . . . . . . . . . . 4 Local User Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Injection Molding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Fill Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Pack Stage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Cool Stage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Ejection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 SOLIDWORKS Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 SOLIDWORKS Plastics Standard . . . . . . . . . . . . . . . . . . . . . . . . . 8 SOLIDWORKS Plastics Professional . . . . . . . . . . . . . . . . . . . . . . 8 SOLIDWORKS Plastics Premium . . . . . . . . . . . . . . . . . . . . . . . . . 8 This Course . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

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Lesson 1: Basic Flow Analysis Basic Flow Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Element Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Shell Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Solid Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Manual or Automatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Meshing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 The PlasticsManager Tree. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Polymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Using the Databases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Machines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Injection Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Running a Flow Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Pack. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Warp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Cool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Flow Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Fill Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Weld Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Results Adviser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Exercise 1: Basic Flow Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Lesson 2: Detecting a Short Shot Detecting Short Shots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Fill Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Definition Fill Setting Parameters . . . . . . . . . . . . . . . . . . . . . . . . 36 Filling Time and Injection Pressure Considerations. . . . . . . . . . . 37 Report Text File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Flow Front Central Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Pressure at End of Fill. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Design Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Plastics to Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Modeling to Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Thickness Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Simulations After Design Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Exercise 2: Short Shots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

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Lesson 3: Automation Tools Automation Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Duplicate Study. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Copying Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Plastics File Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Batch Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Batch Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Summary and Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Exercise 3: Design Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 Lesson 4: Injection Locations and Sink Marks Injection Locations and Sink Marks . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Injection Location Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Positioning the Injection Location . . . . . . . . . . . . . . . . . . . . . . . . 64 Single vs. Multiple Injection Locations . . . . . . . . . . . . . . . . . . . . 64 Modeling for Injection Locations . . . . . . . . . . . . . . . . . . . . . . . . . 65 Automatic Injection Location Selection . . . . . . . . . . . . . . . . . . . . 65 Predict Flow Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Sink Marks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 Measure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Minimizing Sink Marks in Ribs . . . . . . . . . . . . . . . . . . . . . . . . . . 70 Nominal Wall Thickness Advisor. . . . . . . . . . . . . . . . . . . . . . . . . 72 Exercise 4: Minimizing Sink Marks (1) . . . . . . . . . . . . . . . . . . . . . . . 73 Exercise 5: Minimizing Sink Marks (2) . . . . . . . . . . . . . . . . . . . . . . . 77 Lesson 5: Materials Material Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 User-defined Database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Resin Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 Temperature Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Melt Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Mold Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Part Ejection Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Glass Transition Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

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Heat Transfer Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 Specific Heat. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 Thermal Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 Viscosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 PVT Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 Mechanical Properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Thermal Expansion Coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Elastic Modulus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Poisson’s Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Lesson 6: Mesh Manipulation Mesh Manipulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Local Refinement of Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 Mesh Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 Gradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 Element Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 Mesh Editing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Mesh Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Mesh Triangles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Mesh Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Leader Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Solid Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Solid and Shell Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Solid Mesh Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Tetrahedral Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Hexahedral Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Exercise 6: Mesh Repairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 Lesson 7: Detecting Air Traps Detecting Air Traps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 Air Traps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Dieseling Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Plot Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Thickness Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 Venting Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 Venting Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 Exercise 7: Air Traps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

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Lesson 8: Gate Blush Gate Blush. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Runner Elements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Domains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Gate Blush. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 Shear Stress. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 Reducing Gate Blush . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Lesson 9: Packing and Cooling Times Packing and Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 Flow/Pack Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 Pack Stage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 Pack Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 Pack Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 Pack Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 X-Y Plot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Volumetric Shrinkage at End of Packing . . . . . . . . . . . . . . . . . . 145 Clipping Plane Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Setting the Clipping Planes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Isosurface Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Cooling Times. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Temperature at Post-Filling End. . . . . . . . . . . . . . . . . . . . . . . . . 147 Nodal Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 Jetting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Exercise 8: Packing and Cooling Times . . . . . . . . . . . . . . . . . . . . . . 152 Exercise 9: Optimizing Cooling Time . . . . . . . . . . . . . . . . . . . . . . . 155 Multiple Injection Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

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Contents

SOLIDWORKS Simulation

Lesson 10: Multiple Cavity Molds Multiple Cavity Molds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 Mold Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 Channel Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 Runner Channel Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 Runner Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 Element Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 Searching for Polymers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 Clamping Force. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 Clamp Force Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 Clamp Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 Runner Wizard Channel Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 Family Mold Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 Using Runner-Balancing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 Exercise 10: Multiple Cavity Molds. . . . . . . . . . . . . . . . . . . . . . . . . 180 Exercise 11: Runner-Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 Exercise 12: Clamp Force. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 Lesson 11: Symmetry Analysis Symmetry Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 Case Study1: Runner Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 Case Study2: Symmetry Face . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 Symmetry Face . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 Lesson 12: Valve Gates and Hot Runners Valve Gates and Hot Runners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 Hot Runners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 Valve Gates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 Lesson 13: Reaction Injection Molding Reaction Injection Molding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 Reaction Injection Molding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 Lesson 14: Using Inserts Using Inserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 Cavities and Inserts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 Materials for Inserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 Insert Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 Hiding Cavities and Inserts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

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SOLIDWORKS Simulation

Contents

Lesson 15: Multi Shot Mold Multi Shot Mold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 Multi Shot Mold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 Domain Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 Lesson 16: Gas Assistance Molding Gas Assisted Molding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230 Gas Assist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 Material Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 Lesson 17: Cooling Analysis Cooling Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 Cooling Channels and Mold Bodies . . . . . . . . . . . . . . . . . . . . . . . . . 239 Coolant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 Mold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 Cool Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 Cooling Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 Cool Flow Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 Cool Pipe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 Coolant Entrance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 Mold Wall Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 Cool Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 Cool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 Cool Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 Baffle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 Bubbler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 Exercise 13: Cooling Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 Lesson 18: Warpage Analysis Warpage Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 Stages in the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 Shrinkage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 Reducing Shrinkage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 Warpage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 Warp Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263 Warp Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264 Reducing and Fixing Warped Parts. . . . . . . . . . . . . . . . . . . . . . . . . . 267 Thermal Contributions to Warping. . . . . . . . . . . . . . . . . . . . . . . 267 Typical Warp Shapes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 Residual Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271

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Contents

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SOLIDWORKS Simulation

Introduction

1

Introduction

About This Course

SOLIDWORKS Simulation

The goal of this course is to teach you how to use SOLIDWORKS Plastics to optimize your part and mold designs for manufacturability so you can maximize part quality, avoid mold rework and decrease time to market. Specifically: 





Identify and avoid part and mold design features that cause injection molding manufacturing defects. Learn the most common SOLIDWORKS Plastics workflows to ensure your part and mold designs are easily manufacturable. Quickly and easily communicate your analysis results with other members of the design-to-manufacturing team.

The tools for working with plastic injection molding simulation in the SOLIDWORKS Plastics software are quite robust and feature rich. During this course, we will cover many of the commands and options in great detail. However, it is impractical to cover every minute detail and still have the course be a reasonable length. Therefore, the focus of this course is on the skills, tools, and concepts central to successfully working with SOLIDWORKS Plastics. Prerequisites

Students attending this course are expected to have the following:  

 

Mechanical design experience Fundamental knowledge of plastic materials, plastic part design and/or injection mold design Completed the course SOLIDWORKS Essentials Experience with the Windows™ operating system

Course Length

The recommended minimum length of this course is 3 days.

Course Design Philosophy

This course is designed around a process- or task-based approach to training. Rather than focus on individual features and functions, a process-based training course emphasizes the processes and procedures you follow to complete a particular task. By utilizing case studies to illustrate these processes, you learn the necessary commands, options and menus in the context of completing plastics simulation and design optimization tasks.

Using this Book

This training manual is intended to be used in a classroom environment under the guidance of an experienced SOLIDWORKS Plastics instructor. It is not intended to be a self-paced tutorial. The examples and case studies are designed to be demonstrated “live” by the instructor.

Laboratory Exercises

Laboratory exercises give you the opportunity to apply and practice the material covered during the lecture/demonstration portion of the course. They are designed to represent typical simulation situations while being modest enough to be completed during class time.

2

SOLIDWORKS Simulation

Introduction

About the Training Files

The files are organized by lesson number. The Case Study folder within each lesson contains the files your instructor uses while presenting the lessons. The Exercises folder contains any files that are required for doing the laboratory exercises. Windows

The screen shots in this manual were made using the SOLIDWORKS software running a mixture of Windows® 7 and Windows 10. You may notice slight differences in the appearance of the menus and windows. These differences do not affect the performance of the software.

User Interface Appearance

Throughout the development of the software, there have been some cosmetic User Interface changes, intended to improve visibility, that do not affect the function of the software. As a policy, dialog images in the manuals which exhibit no functional change from the previous version are not replaced. As such, you may see a mixture of current and “old” UI dialogs and color schemes.

Conventions Used in this Book

This manual uses the following typographic conventions: Convention

Meaning

Bold Sans Serif

SOLIDWORKS commands and options appear in this style. For example, Features > Extruded Cut means click the Extrude Cut icon on the Features tab of the CommandManager.

Typewriter

Feature names and file names appear in this style. For example, Sketch1.

17 Do this step

Double lines precede and follow sections of the procedures. This provides separation between the steps of the procedure and large blocks of explanatory text. The steps themselves are numbered in sans serif bold.

3

Introduction

Use of Color

SOLIDWORKS Simulation

The SOLIDWORKS user interface makes extensive use of color to highlight selected geometry and to provide you with visual feedback. This greatly increases the intuitiveness and ease of use of the SOLIDWORKS software. To take maximum advantage of this, the training manuals are printed in full color. Also, in many cases, we have used additional color in the illustrations to communicate concepts, identify features, and otherwise convey important information. For example, we might show the result of a filleting operation with the fillets in a different color, even though by default, the SOLIDWORKS software would not display the results in that way.

More SOLIDWORKS Training Resources

MySolidWorks.com enables you to be more productive by connecting

Local User Groups

Discover the benefits of the SOLIDWORKS User Group Network (SWUGN). Attend local meetings to hear technical presentations on SOLIDWORKS and related engineering topics, learn about additional SOLIDWORKS products, and network with other users. Groups are led by SOLIDWORKS users just like you. Check out SWUGN.org for more information, including how to find a group in your area.

4

you with relevant SOLIDWORKS content and services - anytime, anywhere, on any device. Plus, with MySolidWorks Training you can enhance your SOLIDWORKS skills on your own schedule, at your own pace. Just go to My.SolidWorks.com/training.

SOLIDWORKS Simulation

Injection Molding

Introduction

There are many methods for manufacturing plastic parts, including: blow molding, vacuum molding, extrusion molding and rotational molding, just to name a few. In this course, we will focus on the most common method for producing plastic parts, injection molding. A complete introduction to injection molding is beyond the scope of this course. However, the basic premise is as follows. The injection molding process starts with solid resin (plastic) which is loaded into a hopper. The resin is then heated and turned by a screw which causes the solid pellets to turn to liquid. If the screw were to stop, the plastic on the inside of the machine would solidify because of the non-Newtonian nature of plastics.

Fill Stage

The liquid resin is then forced under constant velocity into a cavity which is formed by two or more plates. This is known as the “fill” stage. Generally, the cavity is filled to about 99% before the pack stage begins.

Solid Resin Hopper

Liquid Resin

Screw

Mold Plate A Mold Plate B Cavity Gate Runner

Sprue

5

Introduction

SOLIDWORKS Simulation

Pack Stage

The liquid plastic begins to cool as soon as it touches the walls of the mold. This causes the plastic to shrink. To reduce shrinking, additional molten plastic is forced into the mold under constant pressure after the fill stage completes. This is known as the “pack” stage because additional plastic is packed into the mold. The mold is packed until plastic ceases to flow through the gate; a phenomenon known as gate freeze.

Cool Stage

After the pack stage, the plastic continues to cool in the mold until it is cool enough to be ejected. This is known as the “cool” or “pure cooling” stage. It is important to note, cooling occurs throughout the injection molding process but this stage is called the cool stage because little else occurs in this time.

Ejection

Once the part reaches ejection temperatures, it is then ejected from the mold. After it is ejected, it continues to cool to room temperature. Often, the part will be ejected with the sprue, runner and the gate with the gate being cut later in the process.

Cavity Gate Runner

Sprue

6

SOLIDWORKS Simulation

SOLIDWORKS Plastics

Introduction

SOLIDWORKS Plastics makes use of a process called the finite volume method to simulate fluid flow and heat transfer in the fill, pack, and cooling stages of an analysis. It then makes use of a process called the finite element method to analyze warping. These two methods for solving problems are also used in SOLIDWORKS Flow Simulation and SOLIDWORKS Simulation but to solve different types of engineering problems. In the simulation process, the cavity is first modeled in SOLIDWORKS. Most models are far too complicated to determine flow patterns through. Therefore, the model is represented by many simple shapes which when put together, represent the original cavity. These simple shapes are idealized so that flow can be calculated through them. This collection of shapes is called a mesh and each shape is called an element.

Model

Mesh Elements (representation of model)

Results calculated through mesh elements

There are three packages of SOLIDWORKS Plastics; Standard, Professional and Premium. Each package is designed to simulate various aspects of the injection molding process.

7

Introduction

SOLIDWORKS Simulation

SOLIDWORKS Plastics Standard

SOLIDWORKS Plastics Standard is the package geared towards the plastic part designer. This package is used to simulate the fill stage of the molding process. Using this package, a part designer can determine proper gate locations, view fill patterns and predict if a short shot might occur in addition to other fill related issues.

SOLIDWORKS Plastics Professional

SOLIDWORKS Plastics Professional is the package geared towards mold designers. This package is used to simulate the fill stage, the pack stage and the cool stage. Using this package, a mold maker can balance a family mold layout, predict and reduce packing and cooling times as well as simulate more complicated molding processes.

SOLIDWORKS Plastics Premium

SOLIDWORKS Plastics Premium is the package geared towards plastics analysts. This package is used to simulate all stages of the injection molding process from the fill stage to a post-mold state. Using this package, an analyst can predict how much a part will warp after it has cooled to room temperature. In addition to this, cooling lines can be simulated which leads to more accurate simulations throughout all stages of the mold process.

This Course

This course is divided into three parts. Each part corresponds to a different package of SOLIDWORKS Plastics. Each package of SOLIDWORKS Plastics has a unique user interface which only shows the functionality available in that package. The SOLIDWORKS Plastics Premium user interface is used throughout this course.

8

Lesson 1 Basic Flow Analysis

Upon successful completion of this lesson, you will be able to: 

Create a simulation from scratch.



Understand the available mesh and element types.



Set triangle sizes and mesh a model.



Use input options to select polymer materials and injection locations.



Run and review the results of the analysis.



Predict and display weld lines.

9

Lesson 1

SOLIDWORKS Simulation

Basic Flow Analysis

Basic Flow Analysis

In this lesson, we will perform an analysis of a simple part in order to examine Fill patters and Weld Lines. The process of creating an analysis in SOLIDWORKS Plastics is broken down into three distinct phases; preprocessing, processing and post-processing. We will explore each phase.

Stages in the Process

The major stages in the process are listed below: 

Element types

We will have a discussion on the difference between solid and shell elements. 

Meshing

We will go through the process of selecting an appropriate mesh for the part geometry. 

The Plastics User Interface

We will explore the PlasticsManager tree, the Plastics drop-down menu and the CommandManager. 

preprocessing options

The “preprocessing” options will be explored. These options are used to setup simulations to be run. 

Running a flow analysis

The “analysis phase” includes different types of analyses such as Flow and Flow + Pack. This phase is also known as the processing phase of the analysis. 

Results

The “post-processing” phase allows for the viewing of many types of results, including: plots, animations, charts, and reports. Procedure

10

We will setup a flow analysis which will include the following steps: creating a shell mesh, specifying a polymer material, specifying an injection location, and running the flow analysis. The results will then be viewed.

SOLIDWORKS Simulation

Lesson 1 Basic Flow Analysis

1

Start SOLIDWORKS Plastics. Click the Tools drop-down and then click Add-ins.

This brings up the Add-Ins window. Click both options for SOLIDWORKS Plastics.

Click OK.

2

Open the part file. Open Basic Flow Analysis from the Lesson01\Case Study folder.

Make sure that configuration 200C is active.

11

Lesson 1

SOLIDWORKS Simulation

Basic Flow Analysis

Commands used in SOLIDWORKS Plastics can be found in three locations; the CommandManager, the SOLIDWORKS Plastics pulldown menu and a tree structure called the PlasticsManager Tree.

User Interface

Pull-down menu

CommandManager

PlasticsManager

Units

The Units include two Metric (SI and CGS) and one British setting. The settings affect the units used in the results as well as the triangle size for meshing (see Meshing on page 15). For Metric settings, the triangle size units are mm. For British, they are inches.

Where to Find It



3

CommandManager: Settings and Help

Set units.

Set the units for the analysis. Click Unit - Metrics, SI.

12

> Unit - Metrics > SI

SOLIDWORKS Simulation

Lesson 1 Basic Flow Analysis

Element Types

As stated in Introduction: SOLIDWORKS Plastics on page 7, flow is simulated through a cavity by representing the cavity as a collection of simple shapes. These simple shapes are idealized so that flow can be calculated through them. Each shape is called an element and the collection of elements is called a mesh. The elements that make up the mesh are either Shell (2D) or Solid (3D) in nature. Shell elements cover just the surface of the body while solid elements fill up the volume of the body.

Shell Elements

A Shell mesh is generally used on thin walled parts for obtaining quick results in the early stages of the analysis process. For a shell mesh, the flow profile within the thickness of a shell is deduced from the flow along the shell walls, making it less accurate in many circumstances.

Solid Elements

The Solid mesh can provide accurate results for any type of model, thin or thick. While the run times for a solid mesh are usually longer when compared to those of a shell mesh, a solid mesh should always be used for thick parts. A solid mesh may also provide greater accuracy for models with complex and intricate geometry.

13

Lesson 1

SOLIDWORKS Simulation

Basic Flow Analysis

Manual or Automatic

A mesh can either be created manually or automatically for both solid and shell elements. The Manual method allows the user to control element density; both locally and globally. (The terms local and global are used to describe a specific region of the model or the entire model, respectively.) The Automatic method considers the geometry and places a denser mesh on smaller features without user input.

Where to Find It

  

PlasticsManager Tree: Shell or Solid CommandManager: Mesh Drop-down > Shell or Solid Menu: Tools, SOLIDWORKS Plastics, Mesh, Shell Mesh or Solid Mesh

4

Select the mesh type.

Click Shell

and click Manual.

Click Next on the first page of the Shell Mesh PropertyManager to accept the default parameters.

Note

14

The options presented in the Shell Mesh PropertyManager are dependent on the geometry and package of SOLIDWORKS Plastics used. These options will be explored throughout this course.

SOLIDWORKS Simulation

Lesson 1 Basic Flow Analysis

Meshing

The Surface Mesh page defines the size of the triangles used to create the mesh. The size also determines the number of nodes and elements within the mesh.

Element

Node

Refinement and Repairs

The meshes can be repaired and refined in selected areas. For information on repairing meshes, see Lesson 6: Mesh Manipulation. For information on mesh refinement, see Local Refinement of Mesh on page 93.

Number of Triangles

The number of triangles in the mesh has an impact on calculation times. Each triangle has three nodes and calculations are performed on each node. So, as the number of triangles increase, compute times increase. That said, element counts up to 100,000 should solve in a reasonable amount of time, while element counts over 100,000 may take longer to solve.

15

Lesson 1

SOLIDWORKS Simulation

Basic Flow Analysis

5

Mesh size.

Select the body from the Mesh Groups list. Enter a Triangle Size of 7 mm. Click Mesh.

This triangle size does not result in an accurate representation of the part geometry. 6

Reduce triangle size.

Select the body from the Mesh Groups list. Enter 3 mm for the Triangle Size and click Mesh.

The mesh looks much better. In the next step, we will validate the mesh to see if it is acceptable. Click Next

16

.

SOLIDWORKS Simulation

Lesson 1 Basic Flow Analysis

7

Mesh summary. The mesh Summary appears, listing important qualities of the mesh. The Bad Elements and Very Bad Elements are listed as 0%. These

parameters will be discussed further in Lesson 6: Mesh Manipulation.

Click OK

twice.

17

Lesson 1

SOLIDWORKS Simulation

Basic Flow Analysis

The Plastics Manager Tree

The PlasticsManager Tree contains preprocessing, processing and post-processing settings and commands. Individual commands will be discussed in detail in later lessons. 

MESH - Includes settings to determine and



Material - Contains settings for the selection

edit the type of mesh and runners.







 



of the polymer which will be injected into the mold, the material of the mold and the material of the cooling fluid. Process Parameters - Contains settings for the fill, pack, cool and warpage of the part. Boundary Conditions - Contains settings for specifying the injection location and other simulation specific parameters. ADVISOR - Provides access to the Nominal Wall Thickness advisor. RUN - Starts the analysis. RESULTS - Provides access to the results of the analysis. DISPLAY SETUP - Options for isolines and clipping planes.

Important!

The items displayed in the tree will vary based on the SOLIDWORKS Plastics package installed and the type of analysis being performed. The image in the tree above is from SOLIDWORKS Plastics Premium.

Tip

Check marks are added over icons of tasks that have been completed such as Shell .

Material

The material database provides access to thousands of materials. Materials can be applied to cavities, mold bodies, cooling fluids and inserts.

Polymer

Polymers are organized in the material database by family and company. Polymers can be applied to cavities and inserts.

Where to Find It



18

PlasticsManager Tree: Material, double-click Polymer

SOLIDWORKS Simulation

Lesson 1 Basic Flow Analysis

8

Select a polymer.

Click Polymer

.

Click Default Database

.

Click Sort by Family. Browse to the PP folder and expand it. Click (P) BASF / NOVOLEN 1100 H. Click OK.

Using the Databases

If the polymer you require is not in the Default Database, there are a couple of options: 

Use Similar - Look at the Polymer-Material Parameters tab and the Viscosity tab. You may be able to find a substitute polymer with similar parameters in the Default Database.



Create new - Using the User-defined Database

, a new

material can be added. This will be the subject of Lesson 5: Materials.

19

Lesson 1

SOLIDWORKS Simulation

Basic Flow Analysis

Machines

The Machine option is used to define the injection molding machine to be used. The machine database is provided only as a reference. The selection of a machine does not have any effect on the analysis. For SOLIDWORKS Plastics Standard, there is one machine: Default Machine.

For SOLIDWORKS Plastics Professional and Premium, there are many more machines listed by Name, Manufacturer and Machine Type.

The defult setting is Default Machine. Where to Find It



PlasticsManager Tree: Expand Process Parameters, right-click Fill Settings, click Open Settings, expand Advanced and click Machine Database

.

Injection Location

The Injection Location is where melted plastic flows from the mold runner system into the part cavity. Multiple locations can be used but a minimum of one is required to run an analysis.

Note

The Injection Location does not create geometry. Rather, it is used to locate a node on the shell where melted plastic will enter. A conical pointer is then displayed at the Injection Location, indicating which node the melted plastic will enter through. The Injection Location is often critical to the success of the plastic injection molding process.

20

SOLIDWORKS Simulation

Lesson 1 Basic Flow Analysis

Important!

When using a shell mesh, the size of the Pointer Diameter does not affect the results. The Pointer Diameter sets the visual display of the conical pointer only. The Pointer Diameter does, however, affect the results of a solid mesh.

Where to Find It



Note

The mesh can be shown or hidden by toggling the Mesh Model option. 9

PlasticsManager Tree: Expand Boundary Conditions, doubleclick Injection Location

Add an injection location.

Click Injection Location

.

Select the gate location on the model as indicated in the image below.

Click Add Location. Click OK

.

21

Lesson 1

SOLIDWORKS Simulation

Basic Flow Analysis

Running a Flow Analysis

As mentioned earlier, the process of creating an analysis in SOLIDWORKS Plastics is broken down into three distinct phases; preprocessing, processing and post-processing. The stages of creating a mesh, applying material and specifying fill settings are preprocessing operations. The next phase is the processing phase, also known as the RUN phase, is where the simulation is calculated. There are several processing options available in SOLIDWORKS Plastics; Flow , , Flow + Pack + Warp and Cool . Flow + Pack

Note

The Flow + Pack

analysis is only available in SOLIDWORKS Plastics Professional. Similarly, Flow + Pack + Warp and Cool are only available in SOLIDWORKS Plastics Premium.

Flow

Flow

Pack

Pack

Warp

Warp

Cool

Cool

Where to Find It



is used to analyze the fill stage.

is used to calculate the packing stage and the pure cooling stage of the analysis.

is used to analyze the shrinkage and warpage of the part due to residual stresses during the injection molding cycle. When using Flow + Pack + Warp , all three stages are performed sequentially during the analysis. is used to analyze how the part cools throughout all stages of the injection molding process. PlasticsManager: Expand RUN and double-click Flow

10 Run.

Click Flow

.

The Analysis Manager pops up. Results appear on the model and can be viewed as the simulation solves.

22

SOLIDWORKS Simulation

Lesson 1 Basic Flow Analysis

Batch Manager

If the Analysis Manager dialog is minimized, the continues to run the analysis and can be accessed through Show hidden icons.

Batch Manager Tip

A SOLIDWORKS part can be closed while the analysis is running.

Flow Results

The results that can be analyzed after a Flow simulation has been performed are known as the Flow Results. They include:                

Fill Time (Default) Pressure at End of Fill Central Temperature at End of Fill Average Temperature at End of Fill Bulk Temperature at End of Fill Flow Front Central Temperature Temperature Growth at End of Fill Shear Stress at End of Fill Shear Rate at End of Fill Volumetric Shrinkage at End of Fill Frozen Layer Fraction at End of Fill Cooling Time Temperature at End of Cooling Sink Marks Gate Filling Contribution Ease of Fill

Note

The available result types differ based on the SOLIDWORKS Plastics package: Standard, Professional, or Premium.

Where to Find It

PlasticsManager: Expand RESULTS, double-click Flow Results

Tip

Each of these results is described in detail within the Results Adviser. See Results Adviser on page 27 for more information.

Fill Time

The Fill Time plot can be used to visualize the profile of the melted plastic as it flows through the mold cavity. Red regions are the last areas to fill while blue regions are the first areas to fill. Fill Time is a key result and is shown automatically when the simulation completes.

Isolines

Some results can be shown using Isolines. Isolines run through a model, indicating where a particular value is constant.

Where to Find It



When viewing a result from the Results PropertyManager: Click Isoline

23

Lesson 1

SOLIDWORKS Simulation

Basic Flow Analysis

11 Fill time.

Under Flow Results

24

, click Fill Time.

Click Isoline

. This will toggle a view of the Isolines on.

Click Isoline

off.

SOLIDWORKS Simulation

Lesson 1 Basic Flow Analysis

12 Animate results.

Click Fill Time and Play Click Stop

.

to stop the animation.

25

Lesson 1

SOLIDWORKS Simulation

Basic Flow Analysis

Weld Lines

Weld Lines are formed by two or more flow fronts that come together.

They can be caused by multiple injection locations, through holes in the part or variations in wall thickness that cause a single flow front to separate into two. Weld lines often result in cosmetic defects in a molded part and the areas near weld lines are weaker and prone to structural failure. The positions of weld lines can be changed by moving injection locations or by making design changes. However, they cannot be eliminated from the part if there are through holes or multiple injection locations. Where to Find It



PlasticsManager: Expand RESULTS, double-click Flow Results and check the box for Weld Lines in the Flow tab.

13 Weld lines. Click Weld Lines.

The plot displays the locations of the weld lines and the angle of the flow field as the weld lines form.

26

SOLIDWORKS Simulation

Lesson 1 Basic Flow Analysis

Results Adviser

The Results Advisor is a pop-up window which defines various result plots available in post-processing. The “traffic light” symbol at the top provides an indication of the manufacturability of your design based on part geometry, material selection, injection location(s), processing parameters and the overall ease or difficulty in filling the mold cavity. A green light indicates a cavity which is easy to fill, a red light indicates failure and yellow indicates that there may be difficulties. The adviser also provides details such as the required injection pressure and clamping force in the dialog below the light.

Where to Find It



When viewing a result from the Results PropertyManager: Click Results Advisor

14 Results Adviser.

Click Results Advisor

.

A green “traffic light” symbol indicates that the mold can be successfully filled as per the Ease of Fill plot. (See next the step.) Close Results Advisor.

27

Lesson 1

SOLIDWORKS Simulation

Basic Flow Analysis

15 Ease of Fill. Click Ease of Fill.

You can see that the part is green, which indicates that this part should easily fill based on the geometry, material selection, injection location and processing parameters. Click OK

.

16 Save and close the file.

28

SOLIDWORKS Simulation

Exercise 1 Basic Flow Analysis

Exercise 1: Basic Flow Analysis

Perform a basic flow analysis using the part provided. This lab uses the following skills:       

Basic Flow Analysis on page 10 Element Types on page 13 Meshing on page 15 The Plastics Manager Tree on page 18 Running a Flow Analysis on page 22 Flow Results on page 23 Weld Lines on page 26

Units: Metric, SI Procedure

Follow the procedure below. 1

Open a part file. Open Basic Flow Analysis from the Lesson01\Exercises folder.

2

Units.

Set the units to Metrics, SI. 3

Mesh.

Create a shell mesh using a Triangle Size of 2mm.

4

Material. Click Polymer.

Click Default Database. Click Sort by Family. Select ABS and the Material (P) Asahi Chemical / STYLAC 120. Click OK.

29

Exercise 1

SOLIDWORKS Simulation

Basic Flow Analysis

5

Injection Location. Add an Injection Location selecting the outer edge near the position

shown below.

6

Run analysis. Run a Flow analysis and view the Results.

Review Fill Time with and without the Weld Lines.

30

SOLIDWORKS Simulation

Exercise 1 Basic Flow Analysis

The Max. Injection Pressure of 100 MPa is reached before the Analysis Manager reaches 90% of the cells filled. Notice the Results Adviser traffic light indicates a failure (red), even though the cavity is able to be completely filled at the machine maximum injection pressure of 100 MPA. Increasing the part wall thickness is one of the best ways to reduce the required injection pressure to fill the part cavity. Changing the part geometry using SOLIDWORKS and rerunning a SOLIDWORKS Plastics analysis is covered in Lesson 2: Detecting a Short Shot.

Note

7

Save and close the file.

31

Exercise 1 Basic Flow Analysis

32

SOLIDWORKS Simulation

Lesson 2 Detecting a Short Shot

Upon successful completion of this lesson, you will be able to: 

Detect a short shot.



Change the model and the fill settings to correct the short shot.

33

Lesson 2

SOLIDWORKS Simulation

Detecting a Short Shot

Detecting Short Shots

This lesson follows the process of predicting a short shot in the fill stage. Short shots occur when molten plastic cools and solidifies before the cavity fills all the way. In this lesson, we will see how an undersized wall thickness can cause this problem to occur. Once the short shot is detected, we will fix the problem by exploring two options: a design change at the part level and the decision of whether or not to use an injection molding machine with higher injection pressure capabilities.

Stages in the Process

The major stages in the process are listed below: 

Detecting short shots

We will explore what a short shot is and how to predict one in the analysis process. 

Report text file

The report text file provides details of the analysis including short shot errors. We will explore this file and how to read it. 

Fixing the short shot

We will fix the short shot by modifying the part geometry and editing the Fill Settings. The Fill Settings are used to set the fill time and temperature. Both methods can be used to fix a short shot. Procedure

In this lesson, we will setup and run a simulation on a part with thin walls. The simulation will show a short shot which we will fix by modifying the thickness of the part and editing the Fill Settings. 1

Open a part file. Open Short Shots from the Lesson02\Case Study folder.

The wall thickness of the outer edges is 0.60mm.

34

SOLIDWORKS Simulation

Lesson 2 Detecting a Short Shot

2

Settings.

Use the following settings to setup a simulation: 

Units - Metrics, SI



Mesh, Shell



- PS, (P) Asahi Polymer Chemical, ASAHI-PS404



Injection Location

- 2mm

- Circular

face on bottom

Fill Settings

As mentioned in Introduction: Fill Stage on page 5, the fill stage is characterized by liquid resin being forced into a cavity under constant velocity. Likewise, the Fill Settings control the parameters of the machine throughout the fill stage. These parameters include: Filling Time, Melt Temperature and Mold Temperature. Changing these parameters can fix the short shot issue but may cause other problems to arise. For example, a hotter mold and a shorter filling time may fix the short shot issue, but changing these parameters will also increase cooling time and molded-in stresses. (An increased cooling time leads to higher cycle times and molded-in stress can cause warpage.) The default values used in the Fill Settings dialog are estimated by the software using the part volume and material manufacturer recommendations for melt and mold temperature.

Where to Find It



PlasticsManager Tree: Expand Process Parameters and doubleclick Fill Settings

35

Lesson 2

SOLIDWORKS Simulation

Detecting a Short Shot

Definition Fill Setting Parameters

Within the Fill Settings, there are several parameters that can be edited. These parameters are defined below: 















- The time required to fill the mold cavity with polymer melt. - The Melt Temperature temperature of the plastic as it enters the gate. - The Mold Temperature temperature of the mold walls during the fill stage. Injection Pressure Limit - The maximum possible pressure of the polymer at the injection location. - The maximum Clamp Force Limit force that can be exerted on the on the cavities to hold them together. Flow/Pack Switch Point Determines the switch between the constant velocity fill stage and the constant pressure pack stage. Generally this is kept at 99% to reduce flash (plastic flowing through the parting line of the core and cavity). Flow Rate Profile Settings Allows for a variable flow rate with time. Fill Time

Temperature Criteria for Short

- If the temperature of the melt front reaches the value set here, a short shot will automatically be detected. This parameter is set to the Glass Transition Temperature by default (see Glass Transition Temperature starting on page 83 for more information).

Shots

36

SOLIDWORKS Simulation

Lesson 2 Detecting a Short Shot

Filling Time and Injection Pressure Considerations

The Fill Time heavily influences Velocity too high the pressure required to fill a cavity. When the Fill Time is short, the velocity is high and a lot of resin travels through the gate all at once. This causes the pressure to increase. On the other hand, Plastic cooling when the Fill Time is long, the velocity is low and the flow front may freeze due to the nonNewtonian nature of molten resin which begins to solidify under low shear. This phenomenon also causes an increase in pressure during the fill stage. Therefore, the graph of injection pressure versus fill time displays a U shape curve as shown in the image. From this graph it can be seen that a fill time exists where a cavity can be injected with the lowest possible pressure. 3

Fill settings.

Click Fill Settings Click Fill Time Click OK

Note

. and enter 0.5 sec.

.

The default values for Melt Temperature, Mold Temperature and Temperature Criteria for Short Shots come from the material database and are material manufacturer recommendations. The default value for Filling Time is estimated based off of the part volume as well as the Melt Temperature and Mold Temperature. The default value for the Injection Pressure Limit is always 100 MPa and the Clamp Force Limit is always 100 metric tons. However, in practice, each machine has a different pressure limit and clamp force.

37

Lesson 2

SOLIDWORKS Simulation

Detecting a Short Shot

4

Run analysis.

Click Flow 5

.

Fill time. The Fill Time result shows that the flow stops well short of filling the

mold; resulting in a short shot.

Report Text File

The Report Text File records data from the analysis including warnings and errors. In this example, an error message appears in the text of the report.

Where to Find It



PlasticsManager: Expand RUN, expand Open Report Text File and double-click Flow Text

6

Report text file.

Click Flow Text

38

.

SOLIDWORKS Simulation

Lesson 2 Detecting a Short Shot

An HTML document opens and an error near the bottom of the text reads: Warning C1002 Pressure has reached the max. inject pressure 100.00 MPa. Error C2005 A short shot has occurred during the Flow Process. Close the HTML document.

Flow Front Central Temperature

The Flow Front Central Temperature measures the temperature of the flow front as it flows through the mold. This result is one of many Flow Results on page 23. 7

Flow front central temperature.

Click Flow Results

.

Click Flow Front Central Temperature.

The plot shows that the melted plastic cools before filling the mold.

39

Lesson 2

SOLIDWORKS Simulation

Detecting a Short Shot

Pressure at End of Fill

The Pressure at End of Fill result is the pressure required to fill the geometry that has been meshed for the simulation. This result can predict the required pressure for the entire mold including the sprue, runner, gate and cavity if all of the geometry is represented in the mesh. This result is one of many Flow Results on page 23. 8

Pressure at End of Fill. Show the Pressure at End of Fill plot.

The Pressure at End of Fill plot indicates that the Injection Pressure Limit of 100 MPa (14507 psi) has been reached. The default Injection Pressure Limit is set to 100 MPa in the Fill Settings. 9

Results Adviser.

Click Results Advisor

.

There is a red “traffic light” symbol indicating that a short shot has been detected. The details are found in the text at the top portion of the Adviser dialog. Several options to address short shots are also discussed. Close the dialog and click OK

40

.

SOLIDWORKS Simulation

Lesson 2 Detecting a Short Shot

Design Changes

One advantage of performing simulations early in the design process is that it becomes easy to make changes to the model based off of the results of the analysis. Because SOLIDWORKS Plastics is integrated directly into SOLIDWORKS, this process is very simple. All that is required is to switch between SOLIDWORKS Plastics and SOLIDWORKS as needed to iterate design changes and update the analysis. The view of the cavity can be toggled to a view of the model through the Cavity Visibility command.

Where to Find It



CommandManager: SOLIDWORKS Plastics > Cavity Visibility

Plastics to Modeling

To switch from SOLIDWORKS Plastics to SOLIDWORKS when making a design change, follow the two step procedure: 1. Click Cavity Visibility off. 2. Click the FeatureManager Design Tree tab

Modeling to Plastics

.

To switch from SOLIDWORKS to SOLIDWORKS Plastics after making a design change, follow the two step procedure: 1. Click the PlasticsManager tab 2. Click Cavity Visibility on.

.

Using Configurations

Working with multiple part configurations is another way to incorporate design changes. See Automation Tools on page 49 for more information on working with configurations.

Thickness Change

In this example, a change to the thickness of part is required to eliminate the short shot issue. This will be done by editing the part. 10 Design change.

Click Cavity Visibility

.

Click the FeatureManager Design Tree and Edit Shell 1 . Change the thickness value from “0.60mm” to “1.20mm”. Click OK

.

41

Lesson 2

SOLIDWORKS Simulation

Detecting a Short Shot

Simulations After Design Changes

Design changes made to the SOLIDWORKS part while using SOLIDWORKS Plastics will require you to remesh the part and perform another analysis. A design change will necessitate the following procedure in SOLIDWORKS Plastics: 1. Recreate the mesh. 2. Reselect the injection location. 3. Reanalyzing and replacing the current results.

Note

The units and material process settings will remain the same. 11 Mesh, injection location and material.

Click the PlasticsManager tab Click Shell

and click Cavity Visibility

on.

and begin the meshing process.

The following message will appear: Do you want to use the previous meshing parameters?

Click Yes. This will retain the prior settings. Remesh the part with the same settings as before. Click Injection Location and add an injection location to the same spot as shown in step 2 on page 35. Click Polymer

and select PS, (P) Asahi Chemical, ASAHI-PS404.

12 Injection Pressure Limit.

Click Fill Settings For the Fill Time

. enter 0.5 sec.

For the Injection Pressure Limit Click OK Note

42

enter 150 MPa.

.

In this example, we increased the Injection Pressure Limit from the default value to a value of 150 MPa. The default value for Injection Pressure Limit is set to 100 MPa because the vast majority of injection molding machines can achieve this pressure. Some more advanced machines can reach pressures between 150 MPa and 200 MPa, and state of the art machines can reach upwards of 240 MPa. If your molder runs one of these more advanced machines, you will most likely be paying top dollar for their services. Rather than increasing the Injection Pressure Limit you can increase the part wall thickness, use a high flow polymer material, increase the melt temperature or increase the mold temperature to reduce the required injection pressure.

SOLIDWORKS Simulation

Lesson 2 Detecting a Short Shot

13 Rerun analysis.

Click Flow

. The following message will appear:

FLOW results exist. Do you want to replace it?

Click Yes. 14 Fill time. Show Fill Time to verify that the

melted plastic now completely fills the mold.

15 Pressure at End of Fill. The Pressure at End of Fill plot indicates that the required pressure is below 85% of the Injection Pressure Limit of 150 MPa.

Note

In the injection molding process, additional pressure losses occur through the runner system and machine nozzle geometry. It is recommended when you are analyzing the part cavity only, the result value for Pressure at the End of Fill be closer to 50% of the maximum injection pressure limit specified for the analysis. 16 Save and close the file.

43

Exercise 2

SOLIDWORKS Simulation

Short Shots

Exercise 2: Short Shots

Detect short shots and make repairs using the part provided. This lab uses the following skills:    

Detecting Short Shots on page 34 Report Text File on page 38 Report Text File on page 38 Flow Front Central Temperature on page 39

Units: Metric - SI Procedure

Follow the procedure below. 1

Open a part file. Open Short Shots from the Lesson02\Exercises folder.

2

Basic settings.

Add these steps in the order shown. Mesh Polymer

Shell 2mm PS, (P) Asahi Chemical, Asahi-PS 404

Injection Location

3

Leave the Injection Pressure Limit at its default value of 100MPa.

Note 4

44

Fill settings. Under Fill Settings, set the Filling Time to 0.40 seconds.

Flow analysis. Run a Flow analysis.

SOLIDWORKS Simulation

Exercise 2 Short Shots

5

Short shot. Show the Fill Time result plot.

It is clear that the cavity does not fill properly. Click OK. 6

Error message. Click Flow Text and search the document for the following error

message: A Short-Shot has occurred during the Flow Process. Close the html document. 7

Design change.

Switch to the FeatureManager design tree and change the Shell 1 feature thickness to 1 mm. 8

Run analysis again.

Re-mesh and re-analyze the part using the same values for mesh, polymer, injection location (Basic settings. on page 44), fill settings (Fill settings. on page 44).

45

Exercise 2

SOLIDWORKS Simulation

Short Shots

9

Ease of fill. Show the Ease of Fill result.

Although the cavity does fill, there are yellow and red areas indicating Moderately difficult to fill and Difficult to fill regions of the cavity

with an Injection Pressure Limit of 100MPa.

46

SOLIDWORKS Simulation

Exercise 2 Short Shots

10 Pressure at End of Fill. Show the Pressure at End of Fill result.

The plot indicates that the required pressure is more than 90% of the default Injection Pressure Limit value of 100 MPa. 11 Design change.

Switch to the FeatureManager design tree and change the Shell 1 feature thickness to 1.25 mm. 12 Run analysis again.

Re-mesh and re-analyze the part using the same values for mesh, polymer, injection location (Basic settings. on page 44), fill settings (Fill settings. on page 44). 13 Results. The Fill Time and Ease of Fill results now both provide acceptable

results. 14 Save and close the file.

47

Exercise 2 Short Shots

48

SOLIDWORKS Simulation

Lesson 3 Automation Tools

Upon successful completion of this lesson, you will be able to: 

Use the Duplicate Study command to create new studies in new configurations.



Use the Copy Study command to copy the setup of one simulation into another.



Run multiple simulations at the same time using the Batch Manager.



Create Summary & Report files.

49

Lesson 3

SOLIDWORKS Simulation

Automation Tools

Automation Tools

This lesson makes use of the Duplicate Study command, the Copy Settings command, the Batch Manager and the Report Generator to automate some of the preprocessing, processing and post-processing stages of the analysis.

Stages in the Process

The major stages in the process are listed below: 

Duplicate Study The Duplicate Study command is used to copy the settings of a

simulation to a new configuration. 

Copy Settings The Copy Settings command is used to copy the settings of a

simulation to another existing simulation. 

Batch Manager The Batch Manager is used to run simulations during off-peak hours

and to manage the processing of simulations. 

Generate Report

Automatically produce a complete report in Microsoft PowerPoint and Word format. Procedure

We will start with a model which has already been setup and run. The Duplicate Study command will be used to create two new simulations.

The properties of one of the duplicated studies will be edited. The Copy Settings command will be used to copy the parameters from one

simulation to another and the gate location of the copied simulation will be edited. The Batch Manager will then be used to run several simulations. The results of one of the simulations will be analyzed using the Generate Report command. 1

Open a part file. Open Model Manager from the Lesson03\Case Study folder.

The part has one configuration and has already been analyzed. Review the setup and results.

50

SOLIDWORKS Simulation

Lesson 3 Automation Tools

Duplicate Study

The Duplicate Study command allows you to copy a simulation to a new configuration. The Duplicate Study command always copies the preprocessing information and can be used to copy the results as well.

Where to Find It



CommandManager: SOLIDWORKS Plastics > Duplicate Study

2

Model manager folder.

Click Duplicate Study

.

Name the new study Duplicate 1. Click Copy without results.

Click OK. 3

Duplicate 2. Activate the Default configuration and repeat the procedure shown in step 2 on page 51.

Name this new study Duplicate 2. You should now have three configurations. 4

Activate Duplicate 1.

5

Edit Duplicate 1.

Click Fill Settings

.

Change the Filling Time (sec) to .5 seconds. Click OK

.

51

Lesson 3

SOLIDWORKS Simulation

Automation Tools

Copying Settings

The Copy Settings command is used to copy preprocessing data from one simulation to another. This includes parameters such as the Material and Process Parameters but not information pertaining to the Mesh or Boundary Conditions.

Where to Find It



Plastics File Management

For every simulation that is created, preprocessing and post-processing data is automatically stored in a folder system. In this folder system, a Plastics Data folder exists with the same name as the part file. The Plastics Data folder is automatically created at the root level of the part.

CommandManager: SOLIDWORKS Plastics > Copy Settings

Below the Plastics Data folder, Configuration Data folders exist. These folders are named after the configurations the studies are attached to. Only one study can exist per configuration. The Duplicate Study command is used to create the configurations and folders while information from existing folders is transfered through the Copy Settings command. 6

Copy parameters across simulations.

Click Copy Settings

.

Right-click on Duplicate 1 and click Copy Parameter. Right-click on Duplicate 2 and click Paste Parameter. A message will appear: Copy the parameters of (Duplicate 1) to (Duplicate 2).

Click OK. 7

Paste parameters again. Click Up.

Expand the Basic Flow Analysis folder. Right-click 200C and click Paste Parameter. Click OK again to exit the warning. Note

This study is the same study run in Lesson 1: Basic Flow Analysis. We will run it again in this lesson with new parameters. Click Copy Settings

52

again to exit the command.

SOLIDWORKS Simulation

Lesson 3 Automation Tools

8

Change gate location for Duplicate 2. Activate the Duplicate 2 configuration.

Click Injection Location

.

Select the current gate and click Delete Injection Location

.

Add a gate on the other side of the part.

Batch Manager

The Batch Manager allows you to run multiple analyses immediately or at a later time.

Batch Controls

The control panel at the bottom of the dialog can be used to add, change or delete the batch analysis jobs. - Add a batch analysis.



Add Analysis



- Used to change the type of analysis, such as Change Analysis Shell - FLOW to Shell - PACK.



Delete Analysis



Move Down

  

- Delete a batch analysis from the list. - Move a batch analysis down the list. Move Up - Move a batch analysis up the list. - Start the batch analysis. Start Stop - Stop the batch analysis.

Where to Find It Batch Manager

53

Lesson 3

SOLIDWORKS Simulation

Automation Tools

9

Add batch job for Duplicate 1.

Click Batch Manager

.

Expand the Lesson03\Case Study\ Model Manager folder. Select the Duplicate 1 folder. Click Shell|Flow. Click Add Analysis

.

The batch analysis job appears in the list at the top of the dialog. 10 Add additional jobs.

Using the same process shown in step 9 on page 54, add the Duplicate 2 folder. Browse to the Basic Flow Analysis folder and add the 200C analysis to the batch process.

11 Run all the simulations.

Click Start Click OK

Note

54

. to exit the Batch Manager.

Using the Batch Analysis tool, a file does not need to be open in order for it to be analyzed.

SOLIDWORKS Simulation

Lesson 3 Automation Tools

12 Analyze the results.

View the results from each of the three simulations.

Summary and Report

The Summary and Report tool is used to automatically gather preprocessing and post-processing information into an easy to read PowerPoint or Word document. This document can include the plastic used, gate locations as well as result graphs. The report is customizable and can also be edited after creation.

Where to Find It



PlasticsManager: Expand RESULTS and double-click Summary and Report

55

Lesson 3

SOLIDWORKS Simulation

Automation Tools

13 Activate Duplicate 1. 14 Initiate report.

Click Summary and Report Click OK

.

.

15 Report generator. Click the Cover tab and type the following text.

56

SOLIDWORKS Simulation

Lesson 3 Automation Tools

16 Introduction. Click the Introduction tab and type the following text. The mold fills correctly. Air traps at the end of fill. Numerous weld lines. 17 Generate Image File. Click the Generate Image File tab and then click the Results tab.

Check the following options:  

Shell_PT_R_1_Max. Inlet Pressure Shell_PT_R_4_Y dir.

For the Flow tab, click these options:          

Shell_FLOW_ Fill Time Shell_FLOW_ Pressure at End of Fill Shell_FLOW_ Central Temperature at End of Fill Shell_FLOW_ Temperature Growth at End of Fill Shell_FLOW_ Shear Stress at End of Fill Shell_FLOW_ Cooling Time Shell_FLOW_ Sink Marks Shell_FLOW_ Ease of Fill Shell_FLOW_ Weld Lines Shell_FLOW_ Air Traps

Click OK. Note

Images will appear briefly as they are generated. 18 Saving.

The following message appears: Report generation finished! Do you want to save to another folder?

Click Yes and save the report to the Desktop location. Note

If another folder is not selected, the file is placed in the analysis folder. 19 Close the file.

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Lesson 3

SOLIDWORKS Simulation

Automation Tools

20 Results.

Expand the Duplicate 1_Report folder. It contains folders, an HTML file and the powerpoint file. Open the powerpoint file Duplicate 1_report.

21 Close all files.

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SOLIDWORKS Simulation

Exercise 3 Design Changes

Exercise 3: Design Changes

Analyze and make design changes using the part with multiple configurations provided. This lab uses the following skills:   

Design Changes on page 41 Copying Settings on page 52 Batch Manager on page 53

Units: Metric

Procedure

Follow the procedure below. 1

Open a part file. Open Design Changes from the Lesson03\Exercises folder.

2

Configuration.

Change the configuration to 100C. 3

Settings.

Use the following settings for SOLIDWORKS Plastics:   

4

Mesh, Shell = 4mm Polymer = ABS, (P) Asahi Chemical / STYLAC 120 Injection Location = Near the midpoint of outer edge as shown

Run analysis. Run a Flow analysis.

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Exercise 3

SOLIDWORKS Simulation

Design Changes

5

Results.

Show and review Fill Time and Ease of Fill.

6

Design change.

Change to the configuration 100S. 7

Copy Settings.

Mesh the model and add an injection location. Use the Copy Settings command to copy the material from the 100C configuration to the 100S configuration. The Copy Settings command does not copy the mesh. Therefore, the mesh and the injection location must be defined before the Copy Settings command can be used.

Note

8

Repeat on other configurations.

Repeat the procedure for as many of the part configurations as you desire. 9

Batch run. Use the Batch Manager to run the

studies and then analyze the results. 10 Save and close the file.

60

Lesson 4

Upon successful completion of this lesson, you will be able to: 

Understand the rules for positioning an injection location.



Predict and minimize sink marks.

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Lesson 4

SOLIDWORKS Simulation

Injection Locations and Sink Marks

Injection Locations and Sink Marks

This lesson follows the process of positioning injection locations and avoiding sink marks. Sink marks occur in relatively thick wall sections that are not packed out well enough to compensate for shrinkage as the part cools. They are called sink marks because the part surface is pulled inward, resulting in visible depressions. In this example, we will investigate a model with several ribs of various thicknesses.

Stages in the Process

The major stages in the process are listed below: 

Positioning an injection location

Single or multiple injection locations can be created within the cavity. Some rules for injection locations are discussed. 

Predict and minimize sink marks

The severity of sink marks can be identified through analysis and reduced by following some general design rules. Procedure

In this lesson, we will analyze a cover for a power tool. This model contains ribs of various dimensions. We will start by determining a suitable injection location using a tool called Automatically Add Locations. After we run the analysis, we will find that some ribs are predicted to cause significant sink marks and other ribs will have only minor sink marks. We will analyze these sink marks using the Measure tool and take a look at the dimensions of the ribs. Finally, we will have a discussion on how to properly design ribs to be both strong and have a minimal effect on sink marks. 1

Open a part file. Open Injection Locations from the Lesson04\Case Study

folder. 2

Settings.

Use the following settings for SOLIDWORKS Plastics:

62



Units - Metrics, SI



Mesh, Shell

- 1.75mm

SOLIDWORKS Simulation

Lesson 4 Injection Locations and Sink Marks

3

Material.

Click Polymer

.

Click Default Database

.

Click Sort by Company. Expand BASF. Click PP / NOVOLEN 1100 H.

Click OK.

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Lesson 4

SOLIDWORKS Simulation

Injection Locations and Sink Marks

Injection Location Rules

There are several considerations when placing an injection location and determining if multiple injection locations are required. The following rules will help identify these locations.

Positioning the Injection Location

When placing an injection location, consider the following suggestions: 









Single vs. Multiple Injection Locations





64

When possible, always inject into a thick section of the part geometry. Using Thickness Analysis and Nominal Wall Thickness advisor will help determine where thick sections of the part geometry are located. Avoid injecting into thin areas of the part. The pressure drop through a thin section will require higher injection pressures to fill and pack out the part. The gate may also completely freeze before the part is fully packed out, resulting in larger sink marks. If possible, place the injection location towards the middle of the part geometry to minimize flow lengths within the mold cavity.

In some cases, a model may require multiple injection locations. Here are some general rules to help determine if multiple injection locations will be beneficial. 

Note

Avoid placing the injection location on highly visible areas of the part. The injection location may appear as a visible defect on that surface. Consider the type of mold you will use:  For a two part mold, it is easiest to inject at the parting line or on the B-Side of the cavity if using a cashew or submarine gate. Alternatively, the mold can be injected from the A-Side if the cavity is injected directly from the sprue.  For three part molds and for hot runner molds, it is easiest to inject from the A-Side of the cavity.

Use a single injection location whenever possible. The mold will be less expensive to machine when using a single injection location. There will also be fewer weld lines when using a single injection location. For large or thin parts like a TV housing, use several injection locations spaced so that each injection location fills equal volumes with uniform pressure distributions. For revolved parts, place 3 or 5 injection locations positioned radially outward from the center. This allows for uniform packing and minimizes the possibility of “oval” deformation as the part cools.

For an example of using multiple injection locations on the same cavity, see Multiple Injection Locations on page 157.

SOLIDWORKS Simulation

Lesson 4 Injection Locations and Sink Marks

Modeling for Injection Locations

Injection Locations can be placed at specific locations if those

Automatic Injection Location Selection

Gates can be placed automatically using the Add Injection Locations Automatically command. This command is used to determine the gate

Where to Find It



locations are defined by the geometry. Use the Split Line command to break a model face into multiple faces and create edges and vertices in the process. The edges shape the elements and force nodes to the vertices where injection locations can be placed.

location(s) resulting in the lowest pressure to fill. However, this command will not consider manufacturability. Therefore, gates created using this method often need to be replaced. PlasticsManager Tree: Boundary Conditions, Injection Location, Add Injection Locations Automatically

Tip

You can add up to 10 injection locations at once automatically.

Predict Flow Pattern

The Predict Flow Pattern command displays an animation of the fill pattern without running a complete simulation.

Where to Find It



PlasticsManager Tree: Boundary Conditions, Injection Location, Predict Flow Pattern

65

Lesson 4

SOLIDWORKS Simulation

Injection Locations and Sink Marks

4

Automatic injection location. Click Add Injection Locations Automatically

and select 1 for the

number of gates.

The gate is added to a location which can not easily be manufactured. We will move the gate to the parting line so that this part can easily be manufactured with a two plate mold.

Note

5

Delete injection location.

Select the injection location and click Delete Injection Location 6

.

Reposition injection location.

Select the location near the midpoint of the circular edge as shown and click Injection Location .

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SOLIDWORKS Simulation

Lesson 4 Injection Locations and Sink Marks

7

Filling pattern.

Click Predict Flow Pattern

Click OK 8

.

Run.

Click Flow Note

and review the predicted flow pattern.

.

Sink marks are reduced in the packing stage of the injection molding process. However, in this simulation, we are only solving for the flow stage and are making assumptions with regards what will happen in the packing and cooling stage. We should, therefore, acknowledge variability in the results.

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Lesson 4

SOLIDWORKS Simulation

Injection Locations and Sink Marks

Sink Marks

Sink Marks occur during the cooling process and appear as depressions

on the surface of the molded part. They can be predicted and displayed by viewing the Sink Marks result in a flow analysis. This result is one of many Flow Results on page 23. 9

Sink marks.

Under Flow Results

, click Sink Marks.

Looking at the Top view, some of the internal ribs are visible as sink marks.

68

SOLIDWORKS Simulation

Lesson 4 Injection Locations and Sink Marks

Measure

The Measure tool is used to measure the location and values of results at selected nodes.

Where to Find It



CommandManager: SOLIDWORKS Plastics > Measure

10 Measure.

Click Measure

and click the sink mark as shown below.

Click the upper right corner of the blue box (check mark appears) and click on a location next to the sink mark.

The magenta box shows the difference in location and results between the two selections. The difference in results (dR) is shown to be 0.022 mm. This means there will be a 0.022 mm indent at this location. The value dR[%] displays the difference in the results over the distance between the two selected points.

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Lesson 4

SOLIDWORKS Simulation

Injection Locations and Sink Marks

11 Measure a thicker rib.

Follow the same procedure to measure the sink marks from the large rib on the handle.

This measurement shows an estimated 0.028 mm indent which is significantly larger than the prior sink mark. 12 Measure the other ribs (optional).

Minimizing Sink Marks in Ribs

Design rules for ribs and fillets can be used to minimize potential sink marks in parts. Here are some rules for rib and fillet sizing. 



Rib Thickness - The base thickness of the rib should fall in the range of 1/2 to 2/3 of the attached parent wall thickness. Rib Fillet - The rib fillet radius should fall in the range of 1/4 to 3/4

of the part thickness. 

70

Draft Angle - The draft angle of ribs should fall in the range of 1.5° to 2.0° per inch of rib length, to facilitate part ejection.

SOLIDWORKS Simulation

Lesson 4 Injection Locations and Sink Marks

13 Section.

Click Cavity Visibility tree .

and switch to the FeatureManager design

Create a Section View using the Right plane and an Offset Distance of 47mm. Two ribs can be seen from the sectioned view.

Parent Wall Thickness

Rib 1

Rib 2

Rib 1 has the proper ratios to minimize sink marks while Rib 2 does

not. The rib thicknesses at the base and fillets compare as follows: 

Parent Wall Thickness = 2.54mm

The thicknesses compare as follows:  

Rib 1 Thickness = 1.37mm = 54% of Parent Wall Thickness Rib 2 Thickness = 1.99mm = 78% of Parent Wall Thickness

The fillets compare as follows:  

Rib 1 Fillet = 0.69mm = 27% of Parent Wall Thickness Rib 2 Fillet = 2.0mm = 79% of Parent Wall Thickness

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Lesson 4

SOLIDWORKS Simulation

Injection Locations and Sink Marks

Nominal Wall Thickness Advisor

The primary design rule for an injection-molded plastic part is to maintain a uniform wall thickness. A uniform wall thickness leads to uniform filling patterns, pressure distributions, cooling times, shear stress and volumetric shrinkage. Parts with uniform wall thicknesses have optimized cycle times and are less likely to warp or deform out of shape. The Nominal Wall Thickness Advisor queries the geometry and determines the overall nominal wall thickness in the model and the percentage deviation from this nominal value.

Where to Find It



PlasticsManager: Expand ADVISOR, double-click Nominal Wall Thickness

14 Nominal Wall Thickness.

Click Nominal Wall Thickness

.

The plot shows percentage deviation from the nominal wall thickness. The thicker portions of the model will likely have larger sink marks. 15 Save and close the file.

72

SOLIDWORKS Simulation

Exercise 4 Minimizing Sink Marks (1)

Exercise 4: Minimizing Sink Marks (1)

Add gate locations automatically and analyze the part for sink marks at the ribs. This lab uses the following skills:  



 

Injection Location Rules on page 64 Positioning the Injection Location on page 64 Automatic Injection Location Selection on page 65 Sink Marks on page 68 Minimizing Sink Marks in Ribs on page 70

Units: Metric - SI Procedure

Open the part and use the following steps to complete the analysis. 1

Open a part file. Open Minimizing Sink Marks 1 from the Lesson04\Exercises

folder. 2

Steps.

Add these steps in the order shown. Mesh Polymer 3

Shell 2mm ABS, Generic material / Generic material of ABS

Injection location.

Automatically add one injection location. The suggested injection location will be changed to an edge because this part will be made with a two plate mold.

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Exercise 4

SOLIDWORKS Simulation

Minimizing Sink Marks (1)

Delete the injection location, select the location shown, and add the injection location. The injection location is on the outer edge and is roughly (90, 37, 0).

4

Run analysis. Run a Flow analysis.

5

Fill time.

Click the result Fill Time.

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SOLIDWORKS Simulation

Exercise 4 Minimizing Sink Marks (1)

6

Sink marks.

Click the result Sink Marks. The bands of color mark each rib of the part from the outside.

7

Design change.

Switch to the FeatureManager design tree and change the following values:  

Rib1, Rib Thickness = 1mm Fillet2, Radius = 0.80mm

75

Exercise 4

SOLIDWORKS Simulation

Minimizing Sink Marks (1)

8

Re-analyze.

Re-mesh and re-analyze the part using the same values for mesh, polymer, and injection location. Run a Flow analysis. The resulting Sink Marks are much smaller than in the previous analysis.

9

76

Save and close the file.

SOLIDWORKS Simulation

Exercise 5 Minimizing Sink Marks (2)

Exercise 5: Minimizing Sink Marks (2)

Predict and reduce the effect of sink marks using the part provided. This lab uses the following skills:  

Sink Marks on page 68 Minimizing Sink Marks in Ribs on page 70

Units: Metric Procedure

Open the part and use the following steps to complete the analysis. 1

Open a part file. Open Minimizing Sink Marks 2 from the Lesson04\Exercises

folder. 2

Basic settings.

Add these steps in the order shown. Mesh Polymer

Shell 1mm (P) Asahi Chemical / STYLAC 120

Injection Location

Analysis 3

Flow

Sink marks. Show the Sink Marks result plot.

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Exercise 5

SOLIDWORKS Simulation

Minimizing Sink Marks (2)

4

Design changes.

Edit the part and make changes to the fillets and ribs as follows:     

5

Fillet9, Radius = 0.25mm Rib1, Rib Thickness = 1mm Rib1, Draft Angle = 1° Rib2, Rib Thickness = 1mm Rib2, Draft Angle = 1°

Re-analyze.

Re-analyze the part using the same settings and check for improvement in the sink marks.

6

78

Save and close the file.

Lesson 5 Materials

Upon successful completion of this lesson, you will be able to: 

Understand the polymer properties required to run a flow simulation.



Create new plastic materials in the User Defined Database.

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Lesson 5

SOLIDWORKS Simulation

Materials

Material Properties

SOLIDWORKS Plastics contains a large library of predefined materials. However, there are many materials that are not yet in the database. A material can be added to the database if the required material properties are known. This lesson follows the process of creating a custom resin.

Stages in the Process

The major stages in the process are listed below: 

Obtain material properties

Before creating a material, the material properties need to be obtained through various testing procedures. 

Enter material properties

Material properties are entered into the User-defined Database. Procedure

Start an analysis. Define and enter the material properties into the database. Run the study. View fill time. 1

Open a part file. Open Cover from the Lesson05\Case Study folder.

2

Settings.

Use the following settings to start the simulation:

80



Units - Metrics, SI



Mesh, Shell

- 2mm

SOLIDWORKS Simulation

Lesson 5 Materials

User-defined Database

The User-defined Database is used to create and store custom materials. Custom materials can be created in one of two ways. The first, and easiest way, is to copy and paste an existing material from the Default Database into the User-defined Database then modify the properties from there. The second is to create a new material from scratch. We will create a material from scratch in this lesson.

Material

In SOLIDWORKS Plastics, the term Material is used to define a grouping of resins, metals (for molds) or cooling fluids; while the term Product is used to define a particular resin, metal or cooling fluid. Products and Materials can be created and deleted in the Userdefined Database but not in the Default Database. 3

Create a Material.

Click Polymer

.

Click User-defined Database Click Add Material 4

.

.

Name Material.

Name the material Lesson 5. Click OK. Lesson 5 is now listed in the

database.

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Lesson 5

SOLIDWORKS Simulation

Materials

Resin Properties

A resin is considered “characterized” when its material properties are know. The process of fully characterizing a material requires several tests and can be quite expensive (between $4,000 and $10,000). These material properties will often be supplied by the resin distributer. The properties required to run a simulation will be discussed throughout this lesson and are listed below:

5



Melt Temperature



Mold Temperature



Part Ejection Temperature



Glass Transition Temperature



Specific Heat



Thermal Conductivity



Viscosity



PVT Data



Thermal Expansion Coefficient



Elastic Modulus



Poisson's Ratio

Create a Product. Click Lesson 5 to make it active.

Click Add Product

82

.

SOLIDWORKS Simulation

Lesson 5 Materials

Temperature Properties

Temperature plays a large role in the injection molding process. There are several critical temperatures which must be defined in order to characterize a resin.

Melt Temperature

The Melt Temperature is not the temperature at which the plastic melts. Rather, it is the temperature the resin should be heated to while inside the barrel and the screw. A suggested Melt Temperature must be specified in addition to a Minimum and Maximum allowable range.

Mold Temperature

The Mold Temperature is the temperature the mold maintains throughout the injection molding process. This temperature is controlled through cooling channels that run through the mold plates. Because the mold is constantly being heated from the injected resin and cooled through the cooling channels, a consistent temperature is never fully achieved. A suggested Mold Temperature must be specified in addition to a Minimum and Maximum allowable range.

Part Ejection Temperature

The Part Ejection Temperature is the temperature the part must reach before it is ejected. If the part is ejected before reaching this critical value, the part could deform.

Important!

The Ejection Temperature should be reached throughout the entire part, not just the surface. This is especially true at the locations where pins eject the part from the mold.

Glass Transition Temperature

The Glass Transition Temperature is the temperature at which a resin is considered solid. For semi-crystalline materials, this is a very precise temperature. For amorphous materials, the glass transition is more gradual despite being entered as a single, constant value. 6

Enter Temperature Properties. Enter the values into the Polymer Product Manager as they are listed

in the table blow: Parameter

Value

Polymer Product

SOLIDWORKS Plastic SOLIDWORKS 294 °C 306 °C

Data Source Melt Temperature Max Melt Temperature Min Melt Temperature Mold Temperature Max Mold Temperature Min Mold Temperature Part Ejection Temperature Glass Transition Temperature

281 °C 86 °C 96 °C 71 °C 181 °C 152°C

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Lesson 5

SOLIDWORKS Simulation

Materials

Note

The resin properties used in this lesson are fictitious and are not intended to reflect any existing materials.

Heat Transfer Properties

How heat transfers through a resin during the injection molding process is of critical importance. The Specific Heat and the Thermal Conductivity are two parameters which directly affect heat transfer.

Specific Heat

The Specific Heat is a measure of how much thermal energy it takes to heat up one kilogram of material one degree Kelvin. Therefore, if a material has a high specific heat, it takes more energy to raise its temperature. The specific heat of a material can be measured on a machine called a differential scanning calorimeter.

Thermal Conductivity

The thermal conductivity is used to characterize how easily thermal energy can transfer through a material. In other words, if a material has a high thermal conductivity, it has a low thermal resistance. There are several possible ways of measuring the thermal conductivity for a material. 7

Define the Specific Heat. Click the Specific Heat tab.

Enter 2,200 J/(kg-K).

8

Define the Thermal Conductivity.

Click the Thermal Conductivity tab. Enter .25 W/(m-K).

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SOLIDWORKS Simulation

Lesson 5 Materials

Viscosity

The Viscosity is a measure of how easily fluid can flow. A highly viscous fluid, such as peanut butter, resists flow much more than a low viscous fluid, such as air. Most liquid resins are non-Newtonian which means their viscosity is dependent on the shear rate experienced by the liquid at that moment. In addition to this, resins solidify as they cool. Therefore, the viscosity is also dependent on the temperature. Viscosity is measured using a testing device called a capillary rheometer. You can learn more about the testing procedure from standard, ASTM D3835. 9

Enter Viscosity data. Click the Viscosity tab.

Click Modify 7 parameters Cross model. Enter the following values:

Note

Parameter

Value

D1

7.00e+015 Pa-s

D2

400 K

D3

0 K/Pa

A1

40

A2ba

52 K

tau

700000 Pa

n

.15

There are several methods and models for specifying viscosity data. By clicking Data Fit you can enter raw data for viscosity, temperature and shear rate values.

85

Lesson 5

SOLIDWORKS Simulation

Materials

PVT Data

PVT stands for pressure, volume and temperature. In thermodynamics,

these parameters are often related to one another to determine the state of the material. This information is important for liquid resins because it is used to determine how much the plastic will shrink as it cools during the injection molding process. PVT data can be obtained through the piston apparatus method as outlined in the ISO standard 17744:2004. 10 Enter PVT data. Click the PVT tab.

Click 13: Modified Tait Equation. Enter the following values:

86

Parameter

Value

B1M

8.0e-004 m³/Kg

B2M

5.5e-007 m³/Kg-K

B3M

1.75e+008 Pa

B4M

0.004 1/K

B1S

8.00e-004 m³/Kg

B2S

1.85e-007 m³/Kg-K

B3S

3.40e+008 Pa

B4S

.003 1/K

B5

420 K

B6

3.5e-007 K/Pa

B7

0 m³/Kg

B8

0 1/K

B9

0 1/Pa

SOLIDWORKS Simulation

Lesson 5 Materials

Mechanical Properties

Mechanical properties describe how a material responds to stimuli from a structural perspective. There are several parameters that must be considered.

Thermal Expansion Coefficient

The Thermal Expansion Coefficient is used to describe how a material expands and contracts with regards to changes in the temperature.

Elastic Modulus

The elastic modulus, also known as the Young’s Modulus, is a property which describes the stiffness of a material. More specifically, it describes the relationship between stress and strain. The elastic modulus is obtained through a tensile test often performed on a universal testing machine.

Poisson’s Ratio

As a material deforms under structural load, its volume is not necessarily conserved. The Poisson’s ratio describes how much a material deforms parallel to a load relative to how much it deforms normal to a load. A common way to calculate the Poisson’s ratio is with strain gages on a tensile test.

Note

As the plastic flows, the molecular chains will orient in a particular direction which is dependent on the direction of shear. Because of this, there are two models for each of the mechanical properties; a one constant model and a two constant model. The one constant model assumes that the material behaves uniformly in all directions. The two constant model can be used if the material properties are dependent on the orientation of the molecular chains in the plastic. 11 Define the Thermal Expansion Coefficient. Click the Thermal Expansion Coefficient tab.

Click 1: Constant Coefficient. Enter 0.00005 1/C° for the Thermal Expansion Coefficient. 12 Define the Young’s Modulus. Click the Young Modulus tab.

Click 1: Constant modulus. Enter 2,500 MPa for the Young’s Modulus. 13 Define the Poisson’s Ratio. Click the Poisson’s Ratio tab.

Click 1: Constant modulus. Enter .4 for the Poisson’s Ratio. Click OK. The material SOLIDWORKS Plastic is now created. Click OK again to select it as the polymer.

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Lesson 5

SOLIDWORKS Simulation

Materials

14 Define gate.

Click Injection Location

.

Define the gate at the edge as indicated in the image below.

15 View the Fill Settings.

Click Fill Settings

.

Note how the Melt Temperature and Mold Temperature are brought in directly from the definition of the material. Click OK

.

16 Run the analysis.

Click Flow

.

17 Results.

View the fill time. 18 Close all files.

Save and close the file.

88

Lesson 6 Mesh Manipulation

Upon successful completion of this lesson, you will be able to: 

Apply local mesh refinement.



Learn how a mesh can be repaired.



Convert a shell mesh into a solid mesh.

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Lesson 6

SOLIDWORKS Simulation

Mesh Manipulation

Mesh Manipulation

The mesh, as stated in SOLIDWORKS Plastics on page 7, is a mathematical representation of the original geometry which is used in the simulation process. Creating a mesh which accurately represents the geometry and allows for the simulation to run in a reasonable amount of time often requires manual editing. This lesson follows the process of manipulating the mesh.

Stages in the Process

The major stages in the process are listed below: 

Mesh refinement

Manual mesh refinement allows for a finer mesh in critical areas and a coarser mesh in less critical areas. 

Mesh repairs

Often times, a mesh will have issues when it is being created. There are several tools which can be used to fix these issues. These tools will be explored. 

Solid mesh

A solid mesh is always created from a shell mesh. There are several solid mesh elements available. These elements will be explored. Procedure

Refine a mesh in critical areas where geometric detail is necessary. Repair the mesh in areas that require it. Turn the shell mesh into a solid mesh and discuss the various solid element types. Setup and run a simulation. 1

90

Open a part file. Open Mesh Manipulation from the Lesson06\Case Study folder.

SOLIDWORKS Simulation

Lesson 6 Mesh Manipulation

2

Units.

Set the units of the analysis to Unit - Metrics, SI. In order to create a Solid Mesh (which we will do in this lesson) a Shell Mesh must first be created. The initial Shell Mesh can either be created through the Shell Mesh command or the Solid Mesh

Note

command. 3

Shell Mesh.

Click Shell

and click Manual.

Click Next on the first page of the Shell Mesh PropertyManager to accept the default parameters. Enter .5 mm for the Triangle Size.

The Number of elements (predicted) shows that for a surface mesh, the number of triangles (elements) will be about 219,000 and for a solid mesh, the number of elements will be about 781,000. This is an unreasonable number of elements to have for this particular model. Therefore, we will reduce the overall number of elements by creating larger elements and apply mesh controls to create a denser mesh in critical areas.

Note

4

Reduce mesh size. Enter 1 mm for the Triangle Size.

The Number of elements (predicted) drops to about 55,000 for a surface mesh and about 98,000 for a solid mesh. These values are much more reasonable. Click Mesh.

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Lesson 6

SOLIDWORKS Simulation

Mesh Manipulation

5

Observe the mesh.

At a distance, the mesh appears to be acceptable.

However, there are several locations where the mesh is not representative of the geometry. This can be seen on the small features shown in the image below. Hole in boss (3X)

Holes

We will apply a local mesh control to refine the mesh at these locations.

92

SOLIDWORKS Simulation

Lesson 6 Mesh Manipulation

Local Refinement of Mesh

The mesh is refined through Local Refinement. Local Refinement can be applied on faces, edges or points (vertices).

Mesh Density

The same Mesh Density is not required on all locations of the model: set a fine mesh in more critical areas, a coarse mesh in others. Mesh refinement should also be applied to detailed features.

Gradation

Gradation is used to set the transition between areas of fine mesh and coarse mesh using a slider that moves from Smooth to Sharp. This can

increase (smooth) or decrease (sharp) the total number of elements. Global mesh

Gradation mesh

Refined mesh

6

Set local mesh refinement. Click Delete to remove the current mesh.

Under Local Refinement, click Assign Size. The Assign Size PropertyManager appears.

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Lesson 6

SOLIDWORKS Simulation

Mesh Manipulation

7

Mesh control to the small holes. Set the Triangle Size to .25 mm.

Orient the model to view of the inner faces of the hole pattern. Use a “window selection” to draw a window around the holes.

8

Deselect extra faces.

If any additional faces are selected during the selection process, they can be deselected through Control + click functionality. The remainder of the faces will stay selected. Rotate the part around to ensure you have not selected the top surface on the other side of the part, Control + click to deselect that face if needed. 9

Assign local mesh value. Click Assign to add all the selected faces to the

list.

94

SOLIDWORKS Simulation

Lesson 6 Mesh Manipulation

10 Additional faces. Now, set the Triangle Size to 0.40mm and apply mesh controls to the

faces shown in the picture below. Interior faces of hole

Faces of boss

Interior faces of hole

Click OK

.

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Mesh Manipulation

11 Mesh model.

With the mesh controls applied, click Mesh.

12 Mesh Summary.

Click Next

.

The Summary page opens and indicates that the mesh is not Waterproof. Click OK

.

Element Issues

The quality of the mesh plays a large role in the accuracy of a simulation. Issues in areas like Waterproof, Number of Mesh Group and Aspect Ratio can cause the analysis to fail or adversely affect the results. If problems arise in these areas, they must be repaired.

Waterproof

Elements that fail the Waterproof test have missing faces where ‘water could get in’. This is the case with our current mesh.

Number of Mesh Group

The Number of Mesh Group should correspond to the number of bodies or cavities in the part.

Non-Manifold

Non-Manifold refers to elements that share a boundary with more than

two elements. Aspect Ratio

The Aspect Ratio refers to the ratio of the longest edge to the shortest edge within a single element.

Bad Elements

The elements with an aspect ratio between 8 and 20 are characterized as Bad Elements.

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Very Bad Elements

The elements with an aspect ratio above 20 are characterized as Very Bad Elements.

Unmatched Elements

The Unmatched Elements are the elements at the touching or intersecting faces that do not match. 13 Mesh Editing. The Mesh Editing dialog opens.

Mesh Editing

The Mesh Editing dialog contains informational and editing options that can be used to repair a mesh.

There are four main groups of mesh editing tools. These groups, along with their commands are summarized below: Mesh

This section is used to hide or show elements in the model.

Hide Element

The Hide Element mesh.

command is used to hide or show sections of the

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SOLIDWORKS Simulation

Mesh Manipulation

Mesh Analysis

This section is used to identify and categorize groups of elements.

Summary

The Summary command is used to identify element issues as outlined in Element Issues on page 96.

Topology

The Topology command is used to identify missing faces on the model. Missing faces cause Waterproof errors.

Group

The Group domain.

Quality

The Quality aspect ratios.

Overlap Region

The Overlap Region command is used to identify contacting faces between two bodies where the mesh is incompatible.

Mesh Triangles

This section is used to edit the surface elements (triangles) of the mesh.

Delete

The Delete

Flip Normal Vector

The Flip Normal Vector command is used to reverse the direction of a group of triangles in a mesh.

Fill Hole

The Fill Hole waterproof.

Auto Fill Hole

The Auto Fill Holes command is used to fill all the holes that are detected in the mesh automatically.

Subdivide

The Subdivide command is used to divide selected elements into smaller elements.

Mesh Nodes

This section is used to edit the nodes at the corners of the surface elements (triangles).

Merge

The Merge command is used to merge two or more nodes together which are separated by a distance.

Auto Merge

The Auto Merge command is used to automatically find nodes which are separated by a specified distance and merge them together.

Insert

The Insert command is used to insert a new node at a selected location. New elements are created accordingly.

Adjust

The Adjust node.

Replace

The Replace precisely.

Important!

When editing the mesh, there is no reference to the original geometry. The part’s geometry is only referenced in the initial creation of the mesh. Therefore, it is advisable to only make small changes when editing the mesh triangles and mesh nodes.

98

command is used to identify which elements are in each command is used to identify elements with large

command is used to delete triangle elements.

command is used to repair elements that are not

command is used to adjust the location of a specific command is used to delete and merge selected nodes

SOLIDWORKS Simulation

Lesson 6 Mesh Manipulation

14 Identify holes in the mesh.

Click Topology

and click Edit.

The hole in the mesh which caused the Waterproof warning is outlined in red. This hole will need to be filled.

Click OK

.

15 Fill hole.

Click Fill Hole

and click Edit.

There are several options for filling the hole. To start, we will fill the hole one triangle at a time. Click Fill One Triangle

and zoom into the hole.

Select the nodes in the order shown. A triangle element is formed. 1

2

3

As you can see, this can be a rather time consuming way to fill a hole, especially if the hole is large.

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Mesh Manipulation

16 Fill hole all at once.

Click Fill Hole

.

Select the edge of the rectangle.

The gap is filled with elements that are automatically created.

Click OK

100

.

SOLIDWORKS Simulation

Lesson 6 Mesh Manipulation

17 Identify Bad Elements.

Click Summary

and click Edit.

The Summary shows the mesh is now Waterproof. It also shows that there are 0.00% Bad Elements. As mentioned in Element Issues on page 96, a Bad Element is defined as having an aspect ratio between 8 and 20. However, the Maximum Aspect Ratio within the mesh appears to be 15.39. Considering the total number of elements, it appears that there are less than .005% Bad Elements within the mesh. These elements will be fixed in later steps. Click OK

.

Leader Lines

Leader lines can be used to identify specific types of elements once they have been isolated.

Where to Find It



CommandManager: SOLIDWORKS Plastics > Leader Line

18 Identifying Bad Elements.

Click Quality

and click Edit.

Click the Show elements based on select Range (Aspect Ratio). Click Minimum appear. Click Leader Line

and

and enter 8. Two elements .

The Leader Lines now point to the bad elements. Click OK

.

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Mesh Manipulation

19 Fix bad aspect ratios. Zoom into the Bad Elements on the side of the tab as indicated in the

image below.

Click Auto Merge

and click Edit.

Select the Bad Element from the screen.

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Lesson 6 Mesh Manipulation

Click Apply. The Bad Element is no longer present.

Fix the Bad Element on the other side of the tab as well. Click OK

.

20 Complete Shell Mesh.

Click OK

on the Mesh Editing page.

The Shell Mesh is now complete.

Solid Mesh

A Solid Mesh is made from 3D elements and explicitly represents the inside geometry of a part. In SOLIDWORKS Plastics, a 3D Solid Mesh is created by referencing a typical 2D Shell Mesh. There are several available solid element types which we will explore.

Solid and Shell Mesh

A shell mesh works by interpolating the flow profile between the shell walls. This can be a fair assumption especially in the early stages of analysis (when the accuracy of the results is not as important) and for thin walled parts. A solid mesh, on the other hand, can calculate the flow profile through the thickness of a cavity without interpolating the results. This is why a solid mesh should almost always be used in the later stages of the analysis process.

Solid Mesh Types

There are two main solid element types, tetrahedral and hexahedral. Both element types have several variations thereof.

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Mesh Manipulation

Tetrahedral Elements

Tetrahedral elements are the most commonly used element type because they can represent complicated shapes much more reliably than hexahedral elements. Despite this advantage, tetrahedral elements are more prone to numerical diffusion and are generally slower to solve than hexahedral elements if the number of elements are the same.

Tetrahedral Mesh

In a true Tetrahedral Mesh, only tetrahedral elements are used to represent the geometry. For a solid mesh, it is advisable to have at least 5 elements across the thickness of a part. Therefore, a Tetrahedral Mesh should only be used when the part geometry is thick enough.

Hybrid Mesh

A Hybrid Mesh uses a combination of tetrahedral elements and extruded triangular elements (extruded from the surface) to represent the part geometry. This makes the hybrid approach great for thin parts because more elements are forced across the thickness.

104

Tetrahedral Element

SOLIDWORKS Simulation

Lesson 6 Mesh Manipulation

Hexahedral Elements

Hexahedral Elements are superior in many ways to Tetrahedral Elements. Hexahedrals

Hexahedral Element

solve faster and are less prone to numerical diffusion. However, when working with complicated geometry, hexahedrals are much more difficult to use and often require many more elements than a typical tetrahedral mesh. Voxel Mesh

In a Voxel Mesh, only hexahedral elements are used to represent the geometry and all the elements are oriented in the same direction (orthogonal). Voxel elements are not good at capturing the curvature of complicated geometries but are great for geometrically simple parts.

Marching Mesh

In a Marching Mesh, triangle elements are used on the surface and orthogonal hexahedral elements are used on the inside. A Marching Mesh captures surface geometry and detail much better than a Voxel Mesh.

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Mesh Manipulation

Non-Orthogonal Voxel

In a Non-Orthogonal Voxel Mesh, hexahedral elements are allowed to curve with the part geometry. This leads to geometry which is much more representative of the original geometry.

21 Create a Solid Mesh.

Click Solid

and click Manual.

Under Select Model Type, click Use Shell Mesh Data. Click Next Note

.

The option, Use Shell Mesh Data will make use of the Shell Mesh created earlier in the lesson. The option, Solid Mesh Procedure would take us through the process of creating a Shell Mesh again. A Solid Mesh must always reference a Shell Mesh. 22 Specifying Tetrahedral Elements. Under Solid Mesh Type, click Tetrahedral.

Click Next Note

106

.

The geometry in this model is sufficiently complicated so that we will specify a Tetrahedral Mesh.

SOLIDWORKS Simulation

Lesson 6 Mesh Manipulation

23 Specify Hybrid Mesh. Under Mesh Type click Hybrid.

Click Create Mesh.

Use the Section Clipping Settings sliders to get a 3D view inside the mesh.

Note

The Hybrid Mesh was used because the model has complicated geometry and is thin. Remember, it is advisable to have at least 5 elements across the thickness of a part.

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Mesh Manipulation

24 Complete Mesh.

Click Next

.

Click Next

again to accept the Section Clipping defaults.

Click OK to accept the Solid Mesh Quality and exit out of the Solid Mesh wizard. The mesh is now complete. Note

The Section Clipping page allows you to show and hide domains for a section clipping of the mesh. The Solid Mesh Quality page allows you to analyze the Aspect Ratio of the solid elements in the mesh. 25 Apply Material.

Click Polymer

.

Click Sort by Family. Browse to the ABS folder. Click Asahi Chemical/STYLAC 120. Click OK. 26 Add injection location.

Click Injection Location

.

Specify a Pointer Diameter of 2 mm. Place the gate as indicated below.

Click OK Note

.

The size of the Pointer Diameter indicates how large the gate will be for a Solid Mesh. 27 Run the simulation (optional).

Click Flow

.

The simulation takes 30 minutes to solve.

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Lesson 6 Mesh Manipulation

28 Results (optional). View the Fill Time.

The part experiences a short shot. Save and close the file.

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Exercise 6

SOLIDWORKS Simulation

Mesh Repairs

Exercise 6: Mesh Repairs

Create a solid mesh and eliminate errors that arise during mesh creation. This lab uses the following skills:   

Local Refinement of Mesh on page 93 Mesh Editing on page 97 Solid Mesh on page 103

Units: Metric, SI Procedure

Open the part and use the following steps to complete the analysis. 1

Open a part file. Open Repair Mesh from the Lesson06\Exercises folder.

2

Mesh.

Create a Shell Mesh. Set the default Triangle Size to 2.5 mm. Assign a mesh size of 0.25mm to the grouping of small holes.

Small Holes

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Exercise 6 Mesh Repairs

3

Summary.

Summarize the mesh. The mesh is not Waterproof.

Note

4

Identify hole in mesh. Use the Topology command to find the location of the hole.

5

Fill hole. Use the Fill Hole command to make the mesh Waterproof.

The mesh appears to have some irregular elements. We will investigate further.

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Exercise 6

SOLIDWORKS Simulation

Mesh Repairs

6

Perform a Quality check. Use the Quality check to show Very Bad Element (Aspect ratio

larger than 20). Use Leader Lines to help identify these elements.

7

Delete trouble elements.

Use the Delete command to remove all of the Very Bad Elements in addition to the elements which were created from the Fill Hole command.

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SOLIDWORKS Simulation

Exercise 6 Mesh Repairs

8

Fill Hole. Use the Fill Hole command and specify the Fill One Triangle option to

close the hole.

9

Create a Solid Mesh. Finish the Shell Mesh and create a Solid Mesh which references the Shell Mesh using Tetrahedral, Hybrid elements.

10 Save and close the file.

113

Exercise 6 Mesh Repairs

114

SOLIDWORKS Simulation

Lesson 7 Detecting Air Traps

Upon successful completion of this lesson, you will be able to: 

Detect air traps in the mold cavity.



Perform a venting analysis.

115

Lesson 7

SOLIDWORKS Simulation

Detecting Air Traps

Detecting Air Traps

This lesson follows the process of detecting air traps during the fill stage of the injection molding process. As the cavity fills with melted plastic, the air inside the cavity is displaced. Ideally, this air is vented through machined channels at the parting line or through ejector pins. However, when air is pushed to an area of the cavity where it cannot be easily vented, it is referred to as an “air trap”. Air traps usually cause molded part defects that range from bubbles in the plastic to burn marks caused by the combustion of the trapped air (a phenomenon also known as the “Dieseling Effect”). In this example, a design change will be used to move an air trap to a more manageable location. Venting locations will then be specified to remove any gas which could build up.

Stages in the Process

The major stages in the process are listed below: 

Detecting air traps The Air Traps are displayed with the Fill Time result. They appear



Specify venting locations

graphically as small spherical shapes. Specify where vents will be and see how they affect the air traps. Procedure

116

We will simulate a cavity being filled. We will then examine the results and view air traps in the model. We will make a design change which will move a problematic air trap to a different location where it can be vented. We will then setup venting locations to remove an air trap.

SOLIDWORKS Simulation

Lesson 7 Detecting Air Traps

1

Open a part file. Open Air Traps from the Lesson07\Case Study folder.

2

Units.

Set the units of the analysis to Unit - Metrics, SI. 3

Mesh.

Click Shell

and click Manual.

Specify a mesh with a Triangle Size of 2 mm.

Click OK

4

.

Material.

Click Polymer

.

Click the Default Database. Click the PP folder. Select (P) BASF / NOVOLEN 1100 H. Click OK. 5

Injection Location.

Click Injection Location

.

Specify the Injection Location on the outer edge near the midpoint as shown. Click OK 6

.

Run.

Click Flow

.

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Lesson 7

SOLIDWORKS Simulation

Detecting Air Traps

Race-tracking

When melted plastic is injected into a mold, it will always follow the path of least resistance; generally, the thickest areas of the cavity. When a uniform plastic melt flow front encounters wall sections of various thickness, it will flow into the thickest areas first and the thinnest areas last. This can lead to a phenomenon known as the Race-tracking effect. The Race-tracking effect can be seen here as the flow follows the curve of the thicker section and moves ahead of the center of the flow front. This can cause air traps and weld lines where the flow fronts meet.

Potential air trap and weld lines

Air Traps

The Air Trap option in the Flow Results will show locations of air traps superimposed over the Fill Time plot or other results. They are caused when converging plastic melt flow fronts create an air pocket.

Dieseling Effect

An inadequately vented air trap can result in the Dieseling Effect which occurs when trapped air combusts under compression. The potential damage can result in burn marks on the surface of a part. A potential air trap, like the one seen in this lesson, can often be prevented by avoiding differences in thickness and providing adequate venting.

Plot Ranges

118

The range of a plot can be edited by manipulating the Min and Max parameters when viewing a result. By default the entire range of the plot is shown.

SOLIDWORKS Simulation

Lesson 7 Detecting Air Traps

7

Air trap. Click Fill Time.

Click Air Traps. Click the Max control and drag the scroll wheel so that the fill time is about .36 seconds.

The above result clearly indicates an air trap in the center of the ear piece. Click OK

.

Thickness Analysis

Thickness Analysis is a SOLIDWORKS command that can be used

Note

In some cases, a visual inspection using Section View may provide enough information.

Where to Find It



to find thick regions in a model.



CommandManager: Evaluate > Thickness Analysis Menu: Tools, Thickness Analysis

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Lesson 7

SOLIDWORKS Simulation

Detecting Air Traps

8

Thickness analysis.

Click Thickness Analysis following options:

and set the



Target thickness = 1.27mm Show thick regions = enabled Thick region limit = 2mm Treat corners as zero thickness =



Full color range = cleared

  

enabled Click Calculate.

The circular rib feature is identified as a thicker region. Click OK 9

.

Roll to end.

Click Cavity Visibility

.

Click the FeatureManager Design Tree tab. Drag the rollback bar to the end of the FeatureManager design tree.

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Lesson 7 Detecting Air Traps

The Move Face1 feature decreases the thickness of the circular rib feature as shown below.

10 Mesh, injection location and material.

Click the PlasticsManager tab Click Shell

and click Cavity Visibility

on.

and begin the meshing process.

The following message will appear: Do you want to use the previous meshing parameters?

Click Yes. This will retain the prior settings. Remesh the part with the same settings as before. Click Injection Location and add an injection location to the same spot as shown in step 5 on page 117. Click Polymer and select (P) BASF / NOVOLEN 1100 H as shown in step 4 on page 117. 11 Re-run the analysis.

Click Flow

.

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Lesson 7

SOLIDWORKS Simulation

Detecting Air Traps

12 Re-evaluate air trap. Click the Fill Time results.

Check the Air Traps. Use the Max slider control to view the fill with time. The air trap has moved to a location where it will be easier to vent the cavity. Click OK

.

Venting

It is not always possible to eliminate air traps but they can be moved to places where the air can be vented away. Air traps can be vented by machining small grooves in the mold. The easiest place to do this is on a parting line. The next easiest way to vent the air is by grinding a slot at a pin location. A third option is to vent through a porous section of the mold using vent plugs. Successfully venting the trapped air to the atmosphere will prevent part defects caused by the dieseling effect.

Venting Analysis

In a standard analysis, the effects from the air pushing back on the injected plastic are ignored. However, a Venting Analysis can be performed to take these pressure effects into account. Venting Locations must be specified when performing a Venting Analysis in order to accurately model the effects of the air.

PlasticsManager Tree: Process Parameters, Fill Settings click the Venting Analysis check mark

,

Where to Find It



Venting Locations

When performing a Venting Analysis, Venting Locations must be specified manually.

Where to Find It



Important!

A Venting Analysis can only be performed using a Solid Mesh and the SOLIDWORKS Plastics Professional package or higher. SOLIDWORKS Plastics Professional functionality will be featured throughout the remainder of this course.

122

PlasticsManager Tree: Boundary Conditions, Air Vent

SOLIDWORKS Simulation

Lesson 7 Detecting Air Traps

13 Solid Mesh.

Click Solid

and Manual.

Mesh the model using the Shell Mesh created earlier and Tetrahedral Hybrid elements.

Click OK

.

14 Venting Analysis.

Click Fill Settings

.

Activate Venting Analysis. Leave the Cavity Initial Air Pressure

at

0.1 MPa.

Leave the Cavity Initial Air Temperature at 25 °C. Click OK

Note

.

The Cavity Initial Air Pressure is the initial pressure when the cavity is empty. The Cavity Initial Air Temperature is the initial temperature of the air at the start of the simulation.

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Lesson 7

SOLIDWORKS Simulation

Detecting Air Traps

15 Vent Locations.

Click Air Vent

.

Select elements at the four locations shown.

Click Apply. Click OK Note

.

We will ignore the air trap at by the ear piece to see how much adding venting locations affect the results. 16 Polymer and Gate settings.

Click Polymer and select (P) BASF / NOVOLEN 1100 H as shown in step 4 on page 117. Click Injection Location and add an injection location to the same spot as shown in step 5 on page 117. Specify a Pointer Diameter of 5 mm.

17 Run Venting Analysis.

Click Flow

.

The simulation takes approximately 12 minutes to solve.

124

SOLIDWORKS Simulation

Lesson 7 Detecting Air Traps

18 Venting Pressure. When Venting Analysis is selected under Fill Settings, the Venting Pressure plot becomes available under Fill Results.

Click Venting Pressure.

Note the buildup of pressure at the ear piece. This combination of pressure, air and plastic could cause dieseling to occur. 19 Save and close the file.

125

Exercise 7

SOLIDWORKS Simulation

Air Traps

Exercise 7: Air Traps

Detect air traps and make repairs using the part provided. This lab uses the following skills:    

Air Traps on page 118 Thickness Analysis on page 119 Venting on page 122 Design Changes on page 41

Units: Metric

Procedure

Follow the procedure below. 1

Open a part file. Open Air Traps from the Lesson07\Exercises folder.

2

Thickness analysis. Use Thickness Analysis with 2 mm as the Target Thickness. Select Show thick regions and enter 5.5 mm as the Thick region limit.

The thick area can also be clearly seen using Section View. Click OK.

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SOLIDWORKS Simulation

Exercise 7 Air Traps

3

Mesh.

Create a Shell mesh using a Triangle Size of 1 mm.

4

Polymer. Set the Polymer using Sort by Family. Select the family PP and the type BASF / NOVOLEN 1100 H.

5

Injection Location. Add an Injection Location near the position shown below.

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Exercise 7

SOLIDWORKS Simulation

Air Traps

6

Run analysis. Run a Flow analysis and view the Fill Time with Air Trap.

7

Edit the part.

On the SOLIDWORKS Plastics Command Manager, click Cavity Visibility off.

Click the FeatureManager design tree and edit Sketch3. Change the dimension of the sketch to 1.5 mm and rebuild the part. 8

Remesh and reanalyze.

Remesh the part using the same settings. Add an injection location in the same place and run a Flow analysis. View the Fill Time with Air Traps.

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SOLIDWORKS Simulation

Exercise 7 Air Traps

9

Perform a Venting analysis (optional). Create a Solid Mesh using Tetrahedral Hybrid elements.

Setup the same Polymer and Injection Location (specify a Pointer Diameter of 2 mm). Use the default Venting Analysis options. Add an Air Vent towards the back of the part.

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Exercise 7

SOLIDWORKS Simulation

Air Traps

10 Run a Flow analysis and view the Venting Pressure.

The plot shows a buildup of pressure on the end of the part. This buildup can be easily vented because it lies on the parting line. 11 Save and close the file.

130

Lesson 8 Gate Blush

Upon successful completion of this lesson, you will be able to: 

Specify Runner Elements.



Understand gate blush and how to reduce it.

131

Lesson 8

SOLIDWORKS Simulation

Gate Blush

Gate Blush

This lesson follows the process of creating a solid mesh with runner elements and determining if gate blush is predicted to occur. We will then make a design change to the part which will reduce the shear rate of the resin as it enters the cavity.

Stages in the Process

The major stages in the process are listed below: 

Runner Elements

In this analysis, we will simulate flow through the runner system and the cavity which will be treated as separate entities. 

Gate Blush

We will simulate a phenomenon called gate blush which is caused by excessive shear stress in the resin during fill. We will then make a design change which will reduce gate blush. Procedure

Define a Runner Domain and a Cavity Domain when creating a Solid Mesh. Setup a simulation. Observe the maximum shear rate of the material. Run the analysis. Observe the shear rate experienced by the resin during fill. Modify the gate to reduce shear stress during fill. Rerun the analysis and observe the results. 1

Open a part file. Open Panel Cover from the Lesson08\Case Study folder. The

model contains two bodies. The first body is composed of the cavity and the second body is composed of the sprue, the runner and the gate.

Cavity

Body 1

Runner Gate Sprue

Body 2

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SOLIDWORKS Simulation

Lesson 8 Gate Blush

Runner Elements

In the injection molding process of a standard two plate mold, resin is injected into a runner system before it is injected into the cavity. The runner system and cavity are ejected from the mold at the same time and the runner system is cut off later.

Domains

In SOLIDWORKS Plastics, the term “domain” is used to designate different components in the injection molding process. So far, we have only worked with a single Cavity Domain. However, domains can exist for Runner Systems, Inserts (bodies made of metal or plastic that are over molded by the liquid resin), Cooling Channels and the Mold itself. The purpose of identifying and simulating multiple domains is to create a more realistic simulation by specifying the unique properties of each domain. In our case, understanding the flow of resin into the cavity from the runner system is of critical importance. Therefore, we will model a runner system using a Runner Domain.

Where to Find It

 

2

CommandManager: Assign Domain Domains can be assigned on the second page of the Manual Mesh procedure window.

Runner Domain.

Click Solid

and click Manual.

Click Solid Mesh Procedure. Click Next

.

From the Set Domain Type list, select the body corresponding to the runner system. Click Runner.

Runner System

Click Apply. The runner system changes color.

. Click Next

.

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Lesson 8

SOLIDWORKS Simulation

Gate Blush

3

Complete the Solid Mesh. Set the Triangle Size to 1.6 mm and assign a .4 mm local mesh refinement to the two faces

of the gate. Use Tetrahedral Hybrid elements and default parameters for the remainder of the mesh.

4

Polymer properties.

Click Polymer

.

Click Default Database

.

Click Sort by Family, browse to PA66 and click BASF / ULTRAMID A3EG6.

Gate Blush

After ejection, the runner system is cut from the cavity at the gate. So it makes sense that a small gate produces a small visible mark on the part. However, this is not always the case. Resin is composed of long carbon molecules that can be damaged if the shear rate between the molecules reaches a critical value. These high shear rates are commonly experienced at gate locations due to the amount of plastic flowing through the small opening of the gate. This is known as “gate blush” and it is characterized by a visible mark at the gate location.

Shear Stress

For every resin, there is a maximum recommended shear stress and shear rate. If the polymer exceeds the Max Shear Stress or the Max Shear Rate, it will be damaged. This shear stress is often listed in the definition of the polymer.

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SOLIDWORKS Simulation

Lesson 8 Gate Blush

Reducing Gate Blush

There are several methods for reducing gate blush. Changing the fill time, the melt temperature, the mold temperature, the fill rate profile and the material are all possible solutions. However, the easiest solution is to increase the size of the gate. 5

Max Shear. Click the Polymer-Material Properties tab.

The Max Shear Rate and Max Shear Stress are listed as 60,600 1/s and 500,000 Pa respectively.

Click OK. 6

Fill Settings.

Click Fill Settings Click Fill Time Click OK

. and enter 1 sec.

.

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Lesson 8

SOLIDWORKS Simulation

Gate Blush

7

Injection Location.

Click Injection Location . Set the Pointer Diameter to 7 mm. Place the injection location at the top of the sprue. The machine will inject resin into the mold directly from here.

8

Run the simulation.

Click Flow

.

The simulation takes approximately 15 minutes to solve. 9

Results. Click Shear Stress at End of Fill.

This plot shows that the stress at the gate reached a value of .67 MPa. This value is considerably larger than the Maximum Shear Stress of .5 MPa. Therefore, this part could experience gate blush.

136

SOLIDWORKS Simulation

Lesson 8 Gate Blush

10 Activate larger gate configuration.

This configuration has a much larger gate.

11 Setup model. Follow step 2 on page 133 through step 7 on page 136 to setup the

model. Alternatively, you can use the Copy Settings meshing.

command after

12 Run the simulation.

Click Flow

.

137

Lesson 8

SOLIDWORKS Simulation

Gate Blush

13 Results. The Shear Stress is now .35 MPa, well below the Maximum Shear Stress of .5 MPa.

14 Save and close the file.

138

Lesson 9 Packing and Cooling Times

Upon successful completion of this lesson, you will be able to: 

Determine Packing times.



Determine Pure Cooling times.

139

Lesson 9

SOLIDWORKS Simulation

Packing and Cooling Times

Packing and Cooling

As mentioned in Injection Molding on page 5, there are several stages of the injection molding process. So far, we have explored the fill stage. Now we will focus on the packing and cooling stages. In the injection molding process, the transition from the fill stage to the pack stage is characterized by a velocity controlled fill to a pressure controlled pack. Once the part has finished packing, the pressure is reduced and the mold is allowed to cool in the mold before ejection. This lesson follows the process of determining packing and cooling times.

Stages in the Process

The major stages in the process are listed below: 

Fill to Pack Transition

Generally, the cavity is filled 99% full before the pack stage begins. The reason why the cavity is not filled to 100% of its full capacity is to reduce flash at the weld lines. 

Pack to Cool Transition

During the pack stage, the plastic in the mold cools and shrinks. To reduce these effects, additional plastic is forced through the mold under a controlled pressure. This causes the cooling, shrinking plastic to be forced against the mold walls. The pack stage occurs as long as additional plastic can flow through the gate. Once additional plastic ceases to flow, the pack stage ends and the pure cooling stage begins. 

Cool to Ejection Transition

During the pure cool stage, the pressure is reduced and the part is allowed to cool until it reaches ejection temperature. Ejection temperature should be reached throughout the part, not just at the surface. This is because as the part is ejected, pins push the part out. If the part is still soft in the center during ejection, the pins can perforate or deform the surface of the part. Procedure

Perform a pack analysis and analyze part shrinkage. Reduce the pack times and rerun the analysis. Observe the temperature of the part at the hottest location in the mold and determine the optimum cooling time. 1

Open a part file. Open Panel Cover from the Lesson09\Case Study folder.

This lesson picks up from Lesson 8. The Flow already been performed.

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Lesson 9 Packing and Cooling Times

Flow/Pack Switch

The fill stage is characterized by filling the cavity at a controlled flow rate. The pressure during fill is not constant. It will go up or down in order to for the fill to achieve a controlled flow rate. When the switch from the fill stage to the pack stage occurs, the machine goes from controlling the fill rate to controlling the pressure. 2

View Flow/Pack Switch Point.

Click Fill Settings

.

Expand Advanced. The Flow/Pack Switch Point shows the percentage volume the cavity will be filled to before the pack stage begins. In practice, this switch point is ideally set to 99% in order to reduce flash. However, determining the exact switch point is often performed on the shop floor. We will therefore keep the default, 100%. Click OK

Pack Stage

.

Resin begins to cool and shrink as soon as it touches the mold walls. To counteract these effects, additional plastic is forced into the mold under a controlled pressure. The amount of pressure applied during the pack stage is often a fraction of the pressure applied by the machine during the fill stage and is staggered down, often gradually until the pack stage ends. The end of the pack stage occurs when no more additional plastic can be pushed into the mold. Velocity vs Time V e l o c t y

Switch Point

Time

P r e s s u r e

Pressure vs Time

Switch Point Time

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Pack Settings

The Pack Settings control the Pack Time and Pure Cooling Time as well as the Pressure Profile Settings. The Pressure Profile Settings determine the packing pressure throughout the pack stage. By default the pressure profile is set to 80% of the maximum pressure achieved during the fill stage and is reduced to 40% half way through the pack stage. However, these values can be changed.

Where to Find It



3

PlasticsManager Tree: Expand Process Parameters and doubleclick Pack Settings

Pack Time.

Click Pack Settings

.

Under Pressure Holding Time clear Auto

.

Enter 40 sec. Click OK

.

Note

We will determine the Pure Cooling time after calculating Pressure Holding Time.

Pack Analysis

A Flow analysis must be run before a Pack analysis. A Pack analysis will calculate the pack stage as well as the cooling stage. In order to perform a Flow and a Pack analysis, the Flow + Pack command can be used.

Where to Find It



PlasticsManager: Expand RUN and double-click Pack

or

Flow + Pack 4

Run Pack simulation.

The Flow simulation has already been performed. There is no need to run it again. Click Pack

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Pack Results

The Pack Results include results for understanding the packing process (End of Packing) as well as results for understanding the cooling process (Post-Filling End). The results include the following:             

Where to Find It



Pressure at End of Packing Temperature at End of Packing Bulk Temperature at End of Packing Shear Stress at End of Packing Shear Rate at End of Packing Volumetric Shrinkage at End of Packing Temperature at Post-Filling End Freezing Time at Post-Filling End Residual Stress at Post-Filling End X-Y Plane Birefringence at End of Packing X-Z Plane Birefringence at End of Packing Y-Z Plane Birefringence at End of Packing Frozen Area at Post-Filling End

PlasticsManager: Expand RESULTS and double-click Pack Results

Note

The option to add the Birefringence results must be selected before running the simulation. This option is located in Fill Settings, Advanced, Viscoelastic Birefringence Calculation. Birefringence is an optical property that is applicable to transparent materials and will not generate values for opaque materials.

X-Y Plot

With X-Y Plots, parameters can be plotted against time. Viewing the results from this perspective can provide insight into how the system changes throughout the molding process. The following parameters can be plotted.



Max Inlet Pressure Inlet Flow Rate X-direction Y-direction Z-direction Part Mass Nodal Pressure Nodal Temperature



PlasticsManager: Expand RESULTS and double-click X-Y Plot

      

Where to Find It 5

Mass of Cavity.

Click X-Y Plot

.

Click Part Mass.

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The plot shows that the mass of the part eventually converges to a constant value and appears to completely level off at about 45 seconds. However, from 15 seconds to 45 seconds, the mass of the part only increases by a little more than a gram. Adding 30 seconds to the cycle time may not be worth the increase in part quality. We will experiment by changing the pack time to15 seconds in step 7 on page 145.

Click OK Note

144

.

The plot shows the mass increasing at a constant rate for the first second (fill stage).

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Lesson 9 Packing and Cooling Times

Volumetric Shrinkage at End of Packing

The Volumetric Shrinkage at End of Packing plot displays the reduction of volume during the pack stage. This plot can be used to show how the part will deform and where sink marks will appear. This result is one of many included in Pack Results on page 143. 6

View Volumetric Shrinkage.

Click Pack Results

.

Click Volumetric Shrinkage at End of Packing. Click Runner Visibility from the CommandManager. This will hide the runner system from view.

The plot shows minor shrinkage (around 2.5%) close to the injection location. Click OK 7

.

Change Pressure Holding Time.

Click Pack Settings

.

Change the Pressure Holding Time to 15 seconds. Click OK

.

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8

Rerun the pack.

Click Pack 9

.

Volumetric Shrinkage with shorter pack time.

Click Pack Results

.

Click Volumetric Shrinkage at End of Packing. Click Runner Visibility

.

.

The plot shows an increase in Volume Shrinkage which is what we might expect. Note

146

Whether or not this is an acceptable amount of shrinkage is dependent on how this part will be used. An engineering decision must be made to determine a proper balance between cycle time and part quality.

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Lesson 9 Packing and Cooling Times

Clipping Plane Mode

The Clip Plane Mode command can be used to view the inside of a result plot across a plane.

Where to Find It



When viewing a Result plot > Clipping Plane > Clip Plane Mode

Setting the Clipping Planes

The Clipping Plane section of the dialog is used to set the positions of the clipping planes. Dragging the dial moves the plane in the positive or negative directions from the default “zero” position.

Isosurface Mode

The Isosurface Mode command is used to create a surface within a model were a result maintains a constant value.

Where to Find It



When viewing a Result plot > Clipping Plane > Isosurface Mode

Note

Both the Isosurface Mode option can only be used with solid elements.

Cooling Times

Once the packing times have been determined, the cooling times can be found. Ultimately, the cavity must reach the ejection temperature before the part is ejected so that the part does not warp or deform after it comes out of the mold. This will also prevent the ejector pins from damaging the cavity. (The runner system does not need to reach ejection temperature.)

Temperature at Post-Filling End

The Temperature at Post-Filling End result shows the temperature of the part at the end of the cooling stage. This result is one of many included in Pack Results on page 143.

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10 Clipping Plane of the Temperature at Post-Filling End. Click Temperature at Post-Filling End.

Click Min Note

and enter 225 for the minimum temperature.

The Ejection Temperature for BASF / ULTRAMID A3EG6 is 225 °C. Click Clip Plane Mode

.

Select the Right Plane from the tree. Click Add.

The regions in blue indicate temperatures at or below the ejection temperature. From this plot it appears that the cavity can be ejected safely. An Isosurface mode plot will verify this in the next step. Click Clip Plane Mode

148

to toggle off the section plot.

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11 Isosurface of the Temperature at Post-Filling End.

Click Isosurface . This will show only the regions of the model that are 225 °C and above.

The cavity is below the ejection temperature. This means that the part can be safely ejected. 12 Determine hottest point on the cavity.

Click Min

and enter 165 °C.

The plot shows that the hottest point on the cavity is right at the injection location. Click OK

.

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Nodal Temperature

The Nodal Temperature is an XY Plot temperature of any node against time.

. It allows you to plot the

13 Temperature trend.

Click X-Y Plot

.

Click Set Reference Plane. Under Plane orientation click XY Plane. Drag the slider bar so that the plane is over the hottest point of the cavity and click a node which is close to it. Click Add Grid

.

Click Node Temperature.

The plot shows that the hottest point on the cavity reaches the ejection temperature at about 25 seconds of cycle time. Remember, the fill time was 1 second and the pack time was 15 seconds. This means that an appropriate cool time is around 9 seconds. 14 Save and close the file.

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Jetting

Jetting conditions can occur when the gate diameter is too small, the

injection speed is too high or when there is no wall directly opposite the gate. Jetting can result in a worm- or snake-like pattern on the surface of the part. SOLIDWORKS Plastics can help detect and prevent jetting. .

Follow these steps to check a cavity for jetting: 1. Create Solid mesh refined at the gate. Solid elements must be used. 2. Click Fill Settings and browse to the Solver Settings section. Click Options. 3. For the option (#) Volume of Fluid (VoF) Algorithm (1: Direct, 2: Indirect, 3: CICSAM), select Direct and click OK.

This switches to a different solver. 4. Add all other required settings and run a Flow analysis. 5. View the Fill Time results with Isosurface enabled to check for jetting.

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Exercise 8: Packing and Cooling Times

Create a solid mesh and eliminate gate freeze using the part provided. This lab uses the following skills:    

Local Refinement of Mesh on page 93 Solid Mesh on page 103 Runner Elements on page 133 Packing and Cooling on page 140

Units: Metric, SI

Procedure

Open the part and use the following steps to complete the analysis. This is intended to be an open ended problem. 1

Open a part file. Open Gate Freeze from the Lesson09\Exercises folder.

2

Mesh.

Create a solid mesh and specify Runner elements for the runner body. Use an overall triangle size of 3mm, a refined mesh of 1.5mm on the runner

and sprue faces and a refined mesh of 0.5mm on the gate as shown.Use Tetrahedral, Hybrid elements. 1.5 mm .5 mm 1.5 mm

3

Material.

Add the polymer ABS, (P) Generic material of ABS.

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4

Injection Location.

Add an injection location as shown. Make it large enough to cover the elements at the top of the sprue.

5

Fill and Pack Settings. Note the Fill Time, Pressure Holding Time and Pure Cooling Time.

Keep all the defaults. 6

Flow and Pack. Run a Flow + Pack analysis using the default settings.

7

Mass Vs Time. View the XY Plot for Part Mass.

Note when the when the pack time ends. Is the part fully packed when the cooling stage begins?

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8

Part Shrinkage. View the Volume Shrinkage at End of Packing.

9

Find Pack Times. Extend the Pressure Holding Time to find a pack time that will be

suitable for this part. (This is an open ended task.) 10 Find Cooling Times.

Once you have found a suitable Pressure Holding Time, find a suitable Pure Cooling Time. (This is also an open ended task.) 11 Save and close the file.

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Exercise 9 Optimizing Cooling Time

Exercise 9: Optimizing Cooling Time

Create a solid mesh and optimize the cooling time using the part provided. This lab uses the following skills: 

Clipping Plane Mode on page 147

Units: Metric, SI

Procedure

Open the part and use the following steps to complete the analysis. 1

Open a part file. Open Optimizing Cooling Time from the Lesson09\Exercises

folder. 2

Solid Mesh.

Create a Solid mesh using, tetrahedral, hybrid elements. Use an overall triangle size of 2 mm. 3

Material.

Add the polymer PS, (P) Asahi Chemical, Asahi-PS 404. 4

Injection Location. Add a 3 mm injection location on the edge as shown.

5

Run analysis. Run a Flow + Pack analysis.

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6

Fill time.

Play the animation for Fill Time using Isosurface Mode. Also check the Weld Lines.

7

Sink marks.

Check the result Sink Marks.

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Multiple Injection Locations

Multiple injection locations provide the ability to fill the cavity simultaneously from multiple locations on the geometry. This helps to ensure that the cavity will fill. Unfortunately, multiple injection locations can introduce additional weld lines. 8

Add multiple Injection Locations.

Add two more injection locations on the same edge. Make them roughly equally spaced as shown.

9

Rerun analysis. Run a Flow + Pack analysis, replacing the current analysis.

10 Clipping plane mode. Check the result Fill Time using Clipping Plane Mode.

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11 Design changes.

Change the rib thickness in the part from 10mm to 3mm. Remesh and reanalyze the part.

12 Save and close the file.

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Lesson 10 Multiple Cavity Molds

Upon successful completion of this lesson, you will be able to: 

Create runner elements using Runner Channel Design.



Create runner elements using the Runner Wizard.



Balance runners using the Runner Balancing command.

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Multiple Cavity Molds

Multiple Cavity Molds

This lesson follows the process of creating runner elements using the Runner Channel Design and the Runner Wizard commands. We will also balance a runner system using the Runner Balancing command.

Stages in the Process

The major stages in the process are listed below: 

Multiple cavities

We will open a model with multiple cavities which is connected by a sketch of the runner system. 

Runner Channel Design

Using the sketch connecting the two cavities, we will create a runner system using the Runner Channel Design feature. 

Clamp Force

In order to keep a mold closed during the injection molding process, an enormous amount of force must be exerted to keep the cavities together. The clamping force is often considered a key parameter for part manufacturability. Methods for analyzing this clamping force will be discussed. We will then complete the simulation and analyze the results. 

Runner Wizard

We will start with a model which is mostly complete and create runner elements using the Runner Wizard. The Runner Wizard does not require a sketch or preexisting geometry for creating runner elements. 

Runner Balancing

We will use the Runner Balancing command to automatically size the runner diameters for equal flow in dissimilar cavities. Procedure

We will start with a two cavity model connected by a sketch. We will use the Runner Channel Design command to create runner elements and analyze the mold. We will then open a partially completed study of a different two cavity mold. We will setup a runner system on that model using the Runner Wizard. Finally, we will balance a runner system of a third two cavity mold. 1

Open part file. Open Multiple Cavity Molds from the Lesson10\Case Study folder.

This part consists of two bodies connected by a sketch.

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Mold Layouts

Mold layouts can have different types of arrangements. Some mold layouts are better than others with regards to end product results. A good mold layout achieves equal flow lengths to each part cavity. In the arrangement seen below, the part cavities do not have the same flow length from the sprue. The red arrows show a much longer path from the sprue to the outer cavity than the black arrows.

In the arrangement seen below, all of the part cavities have the same flow length from the sprue and, theoretically, should fill more evenly.

Note

Adding part cavities using powers of two (2, 4, 8...16) into the mold allows you to maximize the parts per cycle while maintaining equal flow lengths to each part cavity.

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2

Review the sketch.

A sketch has been created ahead of time. This sketch will be used as the basis for the runner system. Review the sketch.

The sketch has been split to form two horizontal entities. This is a necessary step when using the Runner Channel Design feature.

Note 3

Mesh the model.

Specify the following settings:

162



Units - Metrics, SI



Mesh, Shell

- 2mm

SOLIDWORKS Simulation

Lesson 10 Multiple Cavity Molds

Channel Design

Runner Elements, as discussed in Runner Elements on page 133, are used to distinguish between cavity systems and runner systems. In Lesson 8: Gate Blush, we modeled a runner system using SOLIDWORKS features which were then specified as Runner Elements. However, this is only one of three ways to specify a runner system. In this lesson we will explore two methods for setting up the runner system using the Channel Design command; through Runner Channel Design and the Runner Wizard Channel Design.

Where to Find It



PlasticsManager Tree: Expand Mesh and double click Channel Design

 

Runner Channel Design

CommandManager: Mesh Drop-down > Channel Design Menu: Tools, SOLIDWORKS Plastics, Mesh, Channel Design

When using the Runner Channel Design option, runner geometry must be designed using 2D or 3D sketches made from lines and arcs. Sketch entities must be connected to the cavity geometry using relations such as Coincident or Pierce. These sketch entities are then used in order to create the components of the runner system; the sprue, runner and the gate. In our model, the sketch entities have been created beforehand.

Sprue

Runner

Gate

Note

The runner sketch geometry can be designed before or after meshing. If you are using a Shell mesh, you will not have to remesh the cavity but you will have to mesh the runner system and will be prompted to rerun the analysis. If you are using a Solid mesh, you will have to remesh the cavity when creating the mesh for the runner system. Adding a new Injection Location will also be required for both mesh types.

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Runner Types

Element Count

Within the Runner Channel Design command, the runner cross section can be specified to have the following profiles. Circle

Square

Half Circle

Rectangular

Trapezoid

Ellipse

The runner Element Count can be increased (Fine) to improve the results, or decreased (Coarse) to reduce the CPU time of the Plastics solver. Line Mesh Fine

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Line Mesh Coarse

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4

Runner.

Click Channel Design

.

Click Runner. Click Circle (this option specifies the profile). Enter the value 6 mm for 1st Point > D1 and enter the value 8 mm for 2nd Point > D2. Enter 9 for the Element Count. Select the vertical line (the sprue) and click Assign.

5

Reverse taper. In the Channel Design PropertyManager click 1,Circle,D1=6.00,D2=8.00 and click Flip Dimension. The taper direction is reversed, the

resulting draft allows for the sprue to be ejected from the mold.

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6

Remaining runners.

Add runners to the remaining four lines using the sizing shown and set the Element Count to 4. When all the runners are completed, click OK

4

.

4 4

1.0

1.0

Note

The horizontal runner is not tapered. It is 4mm at all sections.

Searching for Polymers

Polymers can be selected by family, company or by searching for the name of the polymer. You can also search using custom options such as material groups or limits on material property values.

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7

Searching for a material.

Click Polymer Click Find

.

.

Enter the text stylac 120 and click Find.

Click (P) Asahi Chemical / STYLAC 120 and close the dialog. Click OK. 8

Injection Location.

If the runner is hidden, click .

Runner Visibility

Click Injection Location

.

Add an injection location to the top of the sprue as shown. Click OK

.

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Clamping Force

The clamp force is the amount of force required to keep the mold closed during the injection molding process. This force doubles with two cavities. (Likewise, the force increases by a factor of four with four cavities.)

Clamp Force Limit

Each injection molding machine has a maximum clamping force it can exert. As mentioned in Definition Fill Setting Parameters on page 36, the Clamp Force Limit defines the machine’s maximum clamping force.

Clamp Force

The Clamp Force command is used to define two parameters, the Clamp Force Direction and Excluded Elements. The Excluded Elements section is used to define the locations of the model that do not contribute to the clamping force such as locations on the model that are molded by slides.

Where to Find It

 

9

PlasticsManager Tree: Boundary Conditions, Clamp Force Command Manager: SOLIDWORKS Plastics > Clamp Force

Define Clamp Force Direction.

Click Clamp Force

.

Click Clamp Force Direction. Specify Y as the Clamp Force Direction. Click OK

Note

168

.

We did not specify any Excluded Elements because every location on the model contributes to the clamping load.

SOLIDWORKS Simulation

Lesson 10 Multiple Cavity Molds

10 Fill settings.

Click Fill Settings Click Fill Time

. and enter 0.6 sec.

Click Injection Pressure Limit

and enter 150 MPa.

Observe the Clamp Force Limit which is set to 100 Tonne by default but do not make any changes. Click OK

.

11 Run analysis.

Click Flow

.

12 Fill Time. View the Fill Time result and notice both cavities fill equally.

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13 Pressure at End of Fill. View the Pressure at End of Fill plot.

14 Clamping Force.

Click XY Plot

.

Click Clamp Force. This parameter appears once the Clamp Force Direction has been defined.

Click OK

170

.

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15 Save and close the file.

Runner Wizard Channel Design

The Runner Wizard is another way to create a runner system for common runner layouts. These layouts are listed below: Edge Gate

Submarine Gate

Banana Gate

1-Side Layout

Star Layout

2-Side Layout

Using the Runner Wizard is the fastest way to create a runner system. However, it is limited in the sense that there are only six gate and layout types available. A sketch is not required when using the Runner Wizard.

Note 1

Open part file. Open Runner Wizard from the Lesson10\ Case Study folder.

This part consists of two bodies.

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2

Review Simulation.

A simulation has been partially setup with the following settings: 

Units - Metrics, SI



Mesh, Shell



Polymer



3

- 1.5 mm - PA6, BASF / CAPRON 8200 - Filling Time 1.0 seconds Fill Settings

Runner Wizard.

Click Channel Design

.

Click Runner Wizard. Specify a 1-Side Layout. Select the two locations on the model indicated by the sketch points. Specify the parameters below. Sprue (S)     

Direction: Auto Diameter (SD1): 4 Length (SL): 80 Diameter (SD2): 6 Element Count: 4

Runner (R)  

Diameter (RD): 6 Element Count: 3

Gate (G)    

Diameter (GD1): 6 Length (GL): 8 Diameter (GD2): 1 Element Count: 2

Click OK

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4

Setup gate location.

Click Injection Location

.

Add a gate to the top of the sprue. Click OK 5

Run analysis.

Click Flow

Family Mold Layout

. .

6

Fill time. Plot the Fill Time.

7

Save and close the file.

A family mold is a special type of multi-cavity mold containing two or more different parts which may eventually form an assembly. In a family mold, paired parts have the same color and characteristics because they are created from a single shot. Paired parts rarely have the same volume and fill characteristics, so the runner system of a family mold must be artificially balanced to ensure uniform pressure distribution in each cavity. Once this is achieved, the parts will shrink uniformly and fit together.

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1

Open the mold layout file. Open Runner Balancing from the Lesson10\Case Study folder.

A simulation has already been setup on the part, consisting of two bodies connected by a runner system.

2

Review the simulation.

A simulation has been partially setup with the following settings: 

Units - Metrics, SI



Mesh, Shell

 



- 2.5 mm with .25 mm mesh control on the small holes of the speaker. Polymer - Asahi Chemical - STYLAC 120 - Filling Time of 2.5 seconds and Injection Fill Settings Pressure Limit of 150 MPa Injection Location - top of sprue

3

Run analysis.

4

Fill Time.

Click Flow

.

Click Flow Results

.

Click Fill Time. The lower body fills before the upper body.

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Click the Max slider and move to the instant where the lower body completely fills.

5

Pressure at End of Fill. Plot Pressure at End of Fill. Notice that the pressure required to fill is

quite high and the pressure distribution in the two cavities is unequal. Click OK

.

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Using RunnerBalancing

The Runner-Balancing command is used to automatically adjust the runner diameters to balance the flow between cavities.

Where to Find It



PlasticsManager: Expand Boundary Conditions and click Runner Balancing

6

Original thickness distribution.

Click Runner Balancing and click Show Thickness Distribution. This shows the current diameters graphically.

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7

Runner-Balancing settings. Clear Show Thickness Distribution.

Specify the following settings:     

Max Iteration = 10 Max Diameter = 10 Min Diameter = 2 Max Diameter (Inlet) = 2 Min diameter (Inlet) = 0.8

Click Calculate. The following message shows: Do you want to start the runner balancing analysis?

Click Yes.

The study takes over two hours to complete on a 64-bit computer.

Note 8

Completion message.

When the analysis is complete, a message appears noting the time difference for fill time and the pressure difference before and after runner-balancing. Review the message and click OK.

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9

Balanced thickness distribution. Click Thickness Distribution. The diameters of the runners and gates

have changed to balance the flow.

Click OK Note

.

The sprue diameter is not changed, only the runners and gates. 10 Results.

Click Flow Results

.

View Fill Time to see the results of runner balancing.

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11 Pressure at End of Fill. Plot Pressure at End of Fill.

Click OK

.

12 Save and close the file.

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Exercise 10

SOLIDWORKS Simulation

Multiple Cavity Molds

Exercise 10: Multiple Cavity Molds

Create a multiple cavity mold with runners using the part provided. This lab uses the following skills: Multiple Cavity Molds on page 160  Runner Wizard Channel Design on page 171 Units: Metric, SI 

Procedure

Open the part and use the following steps to complete the analysis. 1

Open a part file. Open Runner Wizard Four Cavity from the Lesson10\Exercises

folder. The part contains 4 bodies/cavities.

2

Setup Simulation.

Start the simulation with the parameters shown below. Mesh Polymer Fill Settings 3

PA6, BASF / CAPRON 8200 Filling Time 1.0 seconds

Runner design. Use the Runner Wizard with a Star layout and specify the following

parameters: Sprue (S) Units:     

180

Shell 1.5mm

Direction: Auto Diameter (SD1): 4 Length (SL): 80 Diameter (SD2): 6 Element Count: 7

SOLIDWORKS Simulation

Exercise 10 Multiple Cavity Molds

Gate (G)   

4

Diameter (GD1): 4 Diameter (GD2): 2 Element Count: 4

Add injection location.

Add an injection location at the top of the sprue. 5

Run analysis. Run a Flow analysis.

6

Fill time.

Show the result plot for Fill Time and animate it.

7

Save and close the file.

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Exercise 11

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Runner-Balancing

Exercise 11: RunnerBalancing

Create a multiple cavity mold with runners and balance the runners using the part provided. This lab uses the following skill: 



Family Mold Layout on page 173 Using Runner-Balancing on page 176

Units: Metric, SI Procedure

Open the part and use the following steps to complete the analysis. 1

Open a part file. Open Runner Balancing from the Lesson10\Exercises folder.

2

Mesh limit.

Mesh the cavities using a Shell Mesh making sure that the meshing process creates less than 10, 000 triangles. 3

Polymer.

Add the polymer PC, Bayer / MAKROLON 1143. 4

Runner design. Use Runner Design to add Runners with diameters as shown below. Use an appropriate Element Count for all the segments. Add an Injection Location at the top of the sprue and run a Flow analysis. 6

6

6

1

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8

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SOLIDWORKS Simulation

Exercise 11 Runner-Balancing

5

Fill time.

Review the Fill Time results. It is clear that the cavities are unbalanced, the smaller cavity completely fills before the larger cavity.

6

Runner balancing. Click Runner Balancing and use the following settings:     

Max Iteration = 10 Max Diameter = 10mm Min Diameter = 2mm Max Diameter (inlet) = 2mm Min Diameter (inlet) = 1mm

Click Calculate. 7

Thickness distribution.

Check the new thickness distribution in the runner, noting the differences in diameters.

8

Save and close the file.

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Clamp Force

Exercise 12: Clamp Force

In this exercise, you will analyze the clamping force of a part with tabs created from sliders. You will also find an appropriately sized injection molding machine. This lab uses the following skill:   

Machines on page 20 Clamping Force on page 168 Clamp Force Limit on page 168

Units: Metric, SI Procedure

Open the part and use the following steps to complete the analysis. 1

Open a part file.

Open slider from the Lesson10\Exercises folder. 2

Shell Mesh. Create a Shell Mesh with a 2.5 mm Triangle Size.

3

Polymer.

Add the polymer ABS, Asahi Chemical / STYLAC 120. 4

Injection Location. Apply an Injection Location to the top of

the model as shown. 5

Clamp Force Limit. Click Fill Settings and browse out to Machine Database

.

Select Allrounder A 270 A 350-70(D18). Click the Clamping Unit tab. Note the Camping Force of 35.1264 Tonne. Note

This is considered a small machine. Some machines within the database, such as the MX Series KM 4000 MX 40000, have a Clamping Force of over 4,000 Tonne. Close the Machine Database page. Click Clamp Force Limit Click OK.

184

and enter 35 Tonne.

SOLIDWORKS Simulation

Exercise 12 Clamp Force

6

Clamp Force.

Click Clamp Force

.

Click Clamp Force Direction and click Y. This part will be manufactured with a sliders to mold the inner tabs. The locations where the sliders abut the mold will not contribute to the Clamp Force. Therefore, we will exclude these faces. Click Excluded Elements and select all the elements on the faces as shown. Click Apply. Repeat the procedure for the three remaining tabs. Click OK. 7

Flow Analysis. Run a Flow study.

8

Analyze the Results. Observe the Clamp Force XY Plot.

Is a larger machine required? If so, find a suitable machine within the Machine Database for this part. 9

Save and close the file.

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Exercise 12 Clamp Force

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SOLIDWORKS Simulation

Lesson 11 Symmetry Analysis

Upon successful completion of this lesson, you will be able to: 

Make use of symmetry to save computational time for a part with multiple cavities.



Create local mesh refinement automatically.

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Symmetry Analysis

Symmetry Analysis

This lesson follows the process of setting up symmetry within a multi-cavity mold. Running an analysis on a multi-cavity mold can be computationally intensive. To reduce the processing time, we can take advantage the symmetry which is often seen in multi-cavity molds.

Stages in the Process

The major stages in the process are listed below: 

Set Symmetry Runner

Setup symmetry on the runner system within the Solid Mesh procedure. 

Symmetry Face

Setup symmetry on a cut model using the Symmetry Face command. 

Automatic local refinement of mesh Use the Automatic option to automatically apply mesh controls to

small features of a model. Procedure

This lesson features two case studies. In the first case study, we will setup symmetry on the runner system within the Solid Mesh command. In the second case study, we will setup symmetry by cutting a model in quarters and using the Symmetry Face command on the symmetric faces.

Case Study1: Runner Design

Using symmetry analysis for runners created with the Channel Design feature. 1

Open a part file. Open Symmetry Analysis CS1 from the Lesson11\Case Study

folder.

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2

Start Meshing.

Click Solid

, Manual.

Click Runner and Cooling System Design. Click Next 3

.

Runner design. Click Runner.

Enter the diameters and the element counts as shown in the image below. Specify 3 elements for the gate.

Click Next Note

.

“EC” stands for Element Count.

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Symmetry Analysis

4

Mesh.

Click Next

to accept the cavity and the runner domains.

Set the Triangle Size to 2.5mm and click Automatic under Local Refinement. Click Mesh.

The Automatic setting for Local Refinement will apply refinement to the model where the overall triangle size may not be sufficient to accurately represent the model geometry. This setting may increase the number of elements substantially in some cases.

Note

5

Symmetrical Runner.

Click Next Click OK Click Next

to accept the surface mesh. at the Summery page. on the Mesh Editing page.

Click Tetrahedral on the Solid Mesh page and click Next Click Symmetrical runner and click Edit.

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Lesson 11 Symmetry Analysis

Under Symmetrical runner setting click 1/4 Symmetry (H-Type).

The multi-cavity mold with the H type runner system is displayed. Click OK 6

Note

.

Solid Mesh. Click Hybrid and Create Mesh.

Due to the use of symmetry, the sprue is only 1/4 of the full-round and the primary runner is only 1/2 of the full-round runner. The simulation will be mirrored about the symmetry faces. Click Next

.

Click Next

on the Section Clipping page.

Click OK

on the Solid Mesh Quality page to complete the mesh.

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Symmetry Analysis

7

Settings.

Use the following settings:

8



Units - Metric, SI



Polymer



Fill Settings

- Asahi Chemical STYLAC 120 - Injection Pressure Limit = 140 MPa

Injection Location.

Click Injection Location

.

Set the Pointer Diameter to 7 mm. Select the center node at the top of the sprue and click Add Location. Click OK 9

.

Flow Analysis (optional).

Click Flow

.

Analyze the results.

Note

The analysis takes over 2 hours on a 64 bit machine with 16GB RAM. The full four cavity analysis took over 13 hours on the same machine. 10 Save and close the file.

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Lesson 11 Symmetry Analysis

Case Study2: Symmetry Face

Symmetry analysis with solid body runners. 1

Open Symmetry Analysis CS2. Open the part Symmetry Analysis CS2 from the Lesson11\ Case Study folder.

The four cavities and the runner system are all modeled as individual solid bodies. 2

Change configuration.

Click ConfigurationManager

.

Activate the Symmetry configuration. This configuration cuts the model with 1/4 symmetry.

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Symmetry Analysis

3

Meshing.

Click Solid

and click Next

.

Select the runner body from the Set Domain Type list, click Runner and click Apply. Click Next

.

Set the Triangle Size to 2.5mm and click Automatic under Local Refinement. Click Mesh. Click Next

.

Finish the mesh with Tetrahedral, Hybrid elements.

Symmetry Face

The Symmetry Face command is used on faces where flow and heat transfer are both symmetrical. The Symmetry Face command is only available for use with solid elements. It can greatly improve solve times.

Where to Find It



PlasticsManager: Expand Boundary Conditions and click Symmetry Face

4

Symmetry Face.

Click Symmetry Face

194

.

SOLIDWORKS Simulation

Lesson 11 Symmetry Analysis

Draw a box around the sprue.

Repeat the procedure for the primary runner. Draw a box inside the runner.

Zoom in to any remaining unselected areas on the runner and click on the elements individually. Make sure not to include any surface of the part cavity. In case any elements from the part cavity are selected, click Delete and repeat the above procedure. Rotate the model and select the other side of the sprue.

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Symmetry Analysis

Click Apply. All the symmetry faces would be highlighted in red. Click OK

5

.

Settings.

Use the following settings:

6



Units - Metric, SI



Polymer



Fill Settings

- Asahi Chemical STYLAC 120 - Injection Pressure Limit = 140 MPa

Injection Location.

Click Injection Location

.

Set the Pointer Diameter to 7 mm. Select any node at the top of the sprue and click Add Location. Click OK 7

.

Flow Analysis (optional).

Click Flow

.

Analyze the results. 8

196

Save and close the file.

Lesson 12 Valve Gates and Hot Runners

Upon successful completion of this lesson, you will be able to: 

Understand the purpose of a hot runner system.



Setup a hot runner system.



Understand the how valve gates operate and why they are used.



Setup valve gates.

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Valve Gates and Hot Runners

Valve Gates and Hot Runners

This lesson follows the process of setting up an analysis with hot runners and a valve gates in order to fill a part which is very long.

Stages in the Process

The major stages in the process are listed below: 

Hot Runners

Valve gates are used exclusively with hot runner systems. The first stage of the process will be to define a hot runner system. 

Valve Gates

Automatic valve gates will be added to the relevant locations. Procedure

Define a Solid Mesh for the cavity and runner system. Apply material, and hot runners. Define a gate and valve system. Analyze the results. 1

Open a part file. Open flower bed from the Lesson12\Case Study folder.

This part consist of two bodies which make up the cavity and the runner system. 2

Mesh.

Click Solid

and Manual.

On the Domains page, specify the runner body using a Runner domain. Specify a 3 mm Triangle Size for the cavity and runner domains. Use default settings for the remainder of the meshing process. 3

Settings.

Use the following settings: 

Units - Metric, SI



Polymer



Fill Settings



198

- (P) Ticona / HOSTALEN GC 7260 - Fill Time - 15 seconds Fill Settings - Clamp Force Limit - 1,200 Tonne

SOLIDWORKS Simulation

Lesson 12 Valve Gates and Hot Runners

4

Gate location.

Click Injection Location

.

Specify a Pointer Diameter of 20 mm at the top of the sprue. Click OK

Hot Runners

.

In a typical two or three plate molding operation, plastic is injected from the machine to the sprue and runner system before it is injected into the cavity. Once cooled, the sprue, runner and cavity are ejected from the mold. The sprue and runner are often separated, reground and used again. However, the properties of the resin degrade after it has been reground. Further complications occur when the plastic is not neat (filled with fiber or with dye added). To solve this problem, hot runner systems are used. In a typical hot runner system, heating coils keep the resin in the runner system at a controlled temperature. In these systems, the sprue and runner are never ejected, thereby reducing waste and have the added benefit of producing parts with exceptional surface finish. However, hot runner systems do add considerable upfront and maintenance costs to the mold, so they are not used all the time.

Where to Find It



PlasticsManager Tree: Boundary Conditions, Filled Hot Runner

5

Hot Runners.

Click Filled Hot Runner

.

Click Temperature and enter 230 °C. This is the temperature the runner system will be heated to. It is also the Melt Temperature of Ticona / HOSTALEN GC 7260. All runner elements are automatically selected when the Filled Hot Runner command is activated. Elements that have been selected within the command appear magenta in color. Click Apply. The elements turn red, indicating their temperature is now controlled. Click OK

.

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Valve Gates and Hot Runners

Note

The Filled Hot Runner command can be used to control the temperature of any element in the model. The process is similar to that seen in Symmetry Face. on page 194.

Valve Gates

Multiple gates are required to fill larger parts. However, when multiple gates release plastic at the same time, weld lines are created where the flow fields meet. Weld lines, as mentioned earlier, cause surface defects and structural weakness. To fix this problem, valve gates are used. (A valve gate is a gate with an on/off switch.) Valve gates can produce parts with high levels of surface finish and strength (such as car bumpers). With valve gates, the filling process starts with at least one gate open. The rest of the valves start closed. Once flow inside the cavity reaches one of the closed gates, the valve opens, releasing additional resin into the cavity. This process continues with additional valves if the part is long enough. By using valve gates, the flow field remains continuous, thereby reducing weld lines. Click Injection Location Control Valve.

and under Type and Selection click

Where to Find It



Note

Hot runner systems are always used with valve gates. 6

Valve gates.

Click Injection Location

.

Under Type and Selection click Control Valve. Under Valve Open Range click Automatic. Click Automatically Add Valves

.

The following warning will appear:

This message means that at least one valve will need to be edited or deleted so that flow can make its way into the cavity. Click OK.

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Lesson 12 Valve Gates and Hot Runners

7

Modify gates.

Select the top valve from the list. Under Valve Open Range click Volume Ratio (%) and leave the default 0% to 100% range. Click Add Valve. This ensures that the first valve will remain open throughout the entire fill process. Click OK

.

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Valve Gates and Hot Runners

8

View Results.

The simulation takes approximately 24 hours to run. A video of the fill time is included in the Case Study folder. Open and view Fill.mp4. Notice how the flow originates from the open valve. As the flow travels past the second valve, it turns on and extends the flow further. The same happens to the third and fourth valves.

9

202

Save and close the file.

Lesson 13 Reaction Injection Molding

Upon successful completion of this lesson, you will be able to: 

Setup and analyze thermoset plastics.



Understand the reaction injection molding process.

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Lesson 13

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Reaction Injection Molding

Reaction Injection Molding

Reaction injection molding, or RIM, is a process by which a resin goes through a chemical reaction in order to harden. These types of resins are also known as thermoset plastics. This lesson follows the process of simulating a thermoset material as it is injected into a mold.

Stages in the Process

The major stages in the process are listed below: 

Thermoset Plastic

There are several predefined thermoset plastics in the database. We will select a thermoset plastic and observe the material properties to see how they differ from that of a thermoplastic material. 

Fill Settings

Thermoset Plastics require different fill settings because heat must be added to the mold rather than taken away. Procedure

Open a part, and mesh with shell elements. Apply a thermoset material to the cavity. Specify Fill settings. Run the analysis and analyze the results. 1

Open a part file. Open Thermoformed Gasket from the Lesson13\Case Study folder.

2

Mesh.

Click Shell

.

Specify an element size of 1 mm. Use default settings for the remainder of the meshing process.

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Lesson 13 Reaction Injection Molding

Reaction Injection Molding

Reaction injection molding, or RIM, is a process by which two reagents are mixed together and injected into a heated mold to react and solidify. Materials used in the reaction injection molding process are classified as thermoset plastics. Once cured, thermoset plastics can have impressive heat and chemical resistance. An important difference between thermoset plastics and conventional thermoplastics is that thermoplastic materials are injected into a mold hot then cooled while in the mold. With thermoset plastics, the process is reversed. Also, thermoplastics can be reground and re-melted while a thermoset plastic cannot. Silicones and polyurethanes are common thermoset plastics.

Note 3

Material.

Click Polymer

and click Sort by Family.

Click LSR. (LSR stands for “liquid silicone rubber”.) Click WACKER/SiliconesElastosil LR 3003/70. Click the Polymer-Material Parameters tab.

Note

Because this is a thermoset material, the Melt Temperature is lower than the Mold Temperature and Ejection Temperature. Click OK.

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Reaction Injection Molding

4

Fill Settings.

Click Fill Settings

.

Click Filling Time

and enter 5 seconds.

Notice that the melt comes into the mold at 85°C and is heated by the mold walls which are maintained at 183°C.

Click OK

5

.

Pack Settings.

Click Pack Settings

.

Notice how the parameter, Pure Cooling Time, indicates that the part

will cool after packing. This is a misnomer. The part will actually be heated during this time. Click OK 6

.

Gate.

Click Injection Location

.

Add a gate to the cavity as indicated in the picture.

Click OK 7

.

Run analysis.

Click Flow + Pack

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.

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Lesson 13 Reaction Injection Molding

8

Note

Temperature at End of Fill. Click Central Temperature at End of Fill.

This plot shows the part heating in the mold; the opposite of a thermoplastic material.

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Lesson 13

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Reaction Injection Molding

9

Pure warming time. View the Central Temperature at Post-Filling End.

Is the part warm enough to be ejected? Or does it need more time to cure in the mold? 10 Save and close the file.

208

Lesson 14 Using Inserts

Upon successful completion of this lesson, you will be able to: 

Simulate over-molding of plastic or metal inserts.



Define cavities and inserts.



Assign materials to inserts.



Hide and show inserts.

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Lesson 14

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Using Inserts

Using Inserts

Plastic can be injected over metal or plastic to create a single part made of multiple materials; a process called ‘over-molding’. This lesson follows the simulation of an over-molded component with multiple copper inserts.

Stages in the Process

The major stages in the process are listed below: 

Cavities and Inserts

We will use domains to distinguish between the cavity bodies and the insert bodies. 

Materials for Inserts

We will assign material properties to the inserts. Inserts can have metal or plastic material properties. 

Hiding Cavities and Inserts

We will use the hide/show functionality to toggle the visibility of the cavity and the inserts in order to get a better view of the results. Procedure

The part contains nine solid bodies, eight of which will be modeled as copper inserts. Flow will be calculated through the cavity. We will analyze the results by examining both the cavity and the inserts. 1

210

Open a part file. Open Using Inserts from the Lesson14\Case Study folder.

SOLIDWORKS Simulation

Lesson 14 Using Inserts

Cavities and Inserts

Solid bodies are classified using domains in SOLIDWORKS Plastics. We have already covered Cavity and Runner domains in Lesson 8: Gate Blush and in this lesson, we will focus on Insert domains. An Insert is a component which is held inside a cavity while melted resin is allowed to flow around it. This results in a single part made of multiple materials held together by plastic. While Cavity domains are always assigned polymer materials, Insert domains can be assigned metal or polymer material properties.

Note

Inserts must be meshed with Solid elements. Shells are not supported. 2

Mesh.

Click Solid

, Manual.

Click Solid Mesh Procedure. Click Next

.

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Using Inserts

3

Hide.

Select the first body in the list and click Hide.

The remaining bodies will be specified as Inserts. 4

Insert Domains.

Select all the visible bodies from the list. Click Insert. Click Apply. 5

Show Cavity. Show the remaining Cavity domain.

Click Next

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.

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Lesson 14 Using Inserts

6

Mesh.

Complete the mesh by specifying a .50 mm Triangle Size and Hybrid, Tetrahedral Elements.

Tip

The elements between the domains must be matched (have shared nodes). If there are any Unmatched Elements, they must be analyzed and fixed.

Materials for Inserts

Materials are applied to inserts through the Inserts command. Inserts can be polymers or metals. The Metal database includes:        

Aluminum Alloys Copper Alloys Iron Other Alloys and Metals Non-metals Steel Titanium Alloys Zinc Alloys

Metals can be added to the User-Defined database by following a similar process to the one outlined in Lesson 5: Materials. Where to Find It

PlasticsManager: Expand Material, Insert

and select Polymer or

Metal

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Lesson 14

SOLIDWORKS Simulation

Using Inserts

7

Specify insert material.

Click Insert

and click Metal.

Select Copper Alloys - Copper. Click OK.

8

Specify cavity material.

Click Polymer

.

Browse out to the PBT class of materials. Select (P) Generic material / Generic material of PBT. Click OK. 9

Fill and pack settings.

Set the following fill and pack settings options: Fill Settings



Pack Settings



214

, Filling Time - 0.4 seconds , Pressure Holding Time - 3 seconds Pack Settings , Pure Cooling Time - 20 seconds



SOLIDWORKS Simulation

Lesson 14 Using Inserts

Insert Settings

The Insert Settings dialog allows you to specify the Insert Part Initial Temperature and the Mold Wall Temperature of the inserts.

Where to Find It

PlasticsManager: Boundary Conditions, Insert Settings 10 Insert settings.

Click Insert Settings

.

Specify the following parameters.  

Insert Part Initial Temperature - 20°C Mold Wall Temperature - 60°C

Click OK

.

11 Injection Location.

Click Injection Location

.

Specify a Pointer Diameter of 1.2 mm to a node on the face as shown. Click OK

.

12 Run analysis.

Click Flow + Pack Note

.

The analysis takes a little over 30 minutes to run.

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Lesson 14

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Using Inserts

13 Fill time. View Fill Time.

Click Isosurface

Note

.

The ‘hook” volume fills slowly and is the last volume to be filled. Ideally, the hook should fill at the same time as the tips of the cavities near the inserts. A design change may be needed to achieve a balanced flow with uniform pressure distribution. Users are encouraged to plot results such as Pressure at End of Fill to see if the cavity has filled evenly. 14 Temperature at end of fill. View Temperature at End of Fill.

Click Clip Plane

216

.

SOLIDWORKS Simulation

Lesson 14 Using Inserts

Hiding Cavities and Inserts

Use Hide/Show Domain to hide and show cavities and inserts when viewing the results. All cavities or all inserts can be toggled between hidden and shown.

Where to Find It



CommandManager: SOLIDWORKS Plastics > Hide/Show Domain

> Cavity/Insert > 1

15 Hide cavity.

Click Hide/Show Domain

.

Click Cavity and 1. The cavity is now hidden. View Temperature at End of Fill with Clipping Plane Mode toggled off to see the inserts

alone. Click OK

.

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Lesson 14

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Using Inserts

16 Show cavity.

Click Hide/Show Domain . Then click Cavity and click 1 to toggle on the visibility of the cavity.

17 X-Y Points.

Click XY Plot

.

Use a Reference Plane with XY Plane orientation. Add the seven points inside and outside the insert cross section as shown.

#1 #7

#4 #2

#3

#6 #5

Note

Points #1 - #3 are inside the cross section of the insert (metal). Points #4 - #7 are outside cross section of the insert but inside the cross section of the cavity boss (polymer).

218

SOLIDWORKS Simulation

Lesson 14 Using Inserts

18 Nodal temperature. Plot the Nodal Temperature using the points. The points on the insert

are colder than those on the cavity.

Note

Since the inserts are made of copper, they heat up very fast due to the high thermal conductivity of copper. Plastic inserts would behave differently. 19 Save and close the file.

219

Lesson 14 Using Inserts

220

SOLIDWORKS Simulation

Lesson 15 Multi Shot Mold

Upon successful completion of this lesson, you will be able to: 

Understand the multi shot molding process.



Setup a two cavity domain analysis.

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Lesson 15

SOLIDWORKS Simulation

Multi Shot Mold

Multi Shot Mold

In a multiple shot molding process, resin is injected into a mold. Then, a section of the mold wall is removed and replaced to form a second cavity against the original cavity. A second material is injected into the new cavity, causing the two materials to form a single part. In this lesson we will simulate the injection molding process of a plastic handle with a rubber finger grip molded into it.

Stages in the Process

The major stages in the process are listed below: 

Domain Order

In a multiple shot molding process, the domain of each cavity must be defined. 

Materials

The materials for each of the domains must then be specified. 

Fill and Pack Settings

The fill and pack settings must be defined for each of the cavities. Procedure

Open the part. Assign domain order through the Solid mesh command. Assign material to each of the domains. Apply gates to the two domains. Specify Fill settings. View the Pack settings. Run a Flow analysis. 1

Open a part file. Open Two Shot from the Lesson15\Case Study folder.

The part consists of two bodies. 2

Mesh the model.

Click Solid

and click Manual.

Click Solid Mesh Procedure. Click Next

222

.

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Lesson 15 Multi Shot Mold

Multi Shot Mold

In more complicated molds, such as tail lights on cars or toothbrush handles, a body will be molded with one type of plastic then molded over with a second type of plastic. There are several ways to do this. One way is to have the part ejected from the first cavity then rotated into the mold of a second cavity. With another method, a section of the first cavity will open and fitted with another mold cavity. Both these operations are variations of multiple shot injection molding. Multiple shot injection molding is an expensive operation but can be used to create impressive plastic components.

Domain Order

In order to specify a second cavity with a second material, a second domain must be specified. This is done on the Domains page of the Mesh PropertyManager. Once a separate domain has been specified, separate Polymer, Fill and Pack Settings can all be assigned to that domain. 3

Domain order. Select the top Cavity from the list.

(The gripper part of the handle.) Under Domain Group, click the drop down and select 2. Click Apply. The gripper changes color from tan to orange. There are now two cavity domains. Click Next 4

.

Finish mesh.

Complete the mesh with a 2.5 mm Triangle Size and Tetrahedral Hybrid elements.

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Lesson 15

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Multi Shot Mold

5

Polymer for domain cavity 1.

Click Polymer

.

At the top, under Domain click Cavity (Part) 1. Click ABS Generic material /Generic material of ABS.

6

Polymer for domain cavity 2. Under Domain click Cavity (Part) 2.

Click DuPont Engineering Polymers / Alcryn 2080 BK.

Click OK.

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Lesson 15 Multi Shot Mold

7

Fill Settings.

Click Fill Settings . Under Domain, toggle between Cavity (Part) 1 and Cavity (Part) 2.

The Fill Settings change between the two cavities. The default Fill Settings are derived from the material applied to each cavity.

Note

Click OK 8

.

Pack Settings.

Click Pack Settings . Under Domain, toggle between Cavity (Part) 1 and Cavity (Part) 2. The Process Parameters of the Pack Settings change between the two cavities in a manor similar to the Fill Settings. However, we will not run a Pack analysis.

Note

Click OK 9

.

Hide Cavity 2.

Click Hide/Show Domain Click Cavity and click 2.

.

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Multi Shot Mold

10 First injection location.

Click Injection Location . Specify a 3 mm gate to the location indicated. Click OK

.

11 Show Cavity 2 and hide Cavity 1.

Click Hide/Show Domain . Click Cavity and click 2. Cavity 2 is now shown. Click Hide/Show Domain Click Cavity and click 1.

.

12 Second injection location.

Click Injection Location

.

Specify a 3 mm gate to the location indicated. Click OK

.

13 Show both Cavities.

Use the Hide/Show Domain show both cavities. 14 Run Flow simulation.

Click Flow

226

.

command to

SOLIDWORKS Simulation

Lesson 15 Multi Shot Mold

15 Fill time.

View Fill Time with Isosurface Mode Click Play

.

to view the animation.

Notice how Cavity 1 fills before Cavity 2. Click OK

.

16 Save and close the file.

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Lesson 15 Multi Shot Mold

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SOLIDWORKS Simulation

Lesson 16 Gas Assistance Molding

Upon successful completion of this lesson, you will be able to: 

Understand the basic premise of gas assisted plastic injection molding.



Setup and analyze a gas assisted plastic injection molding simulation.

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Lesson 16

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Gas Assistance Molding

Gas Assisted Molding

Gas assisted injection molding is a way to reduce the thickness of parts that would otherwise be thick in nature. In a gas assisted molding process, a resin is injected into the cavity so that it is about half way filled. A gas is then injected into the mold, pushing the resin to the outer walls. This lesson follows the simulation of a gas assisted injection molding process.

Stages in the Process

The major stages in the process are listed below: 

Set Co-Injection

In gas assisted injection, two materials are injected into the same cavity. This requires a Co-Injection setup when defining materials, the second material being gas. 

Gate Injection

Once a co-injection is defined, gates must be setup to specify how much of each material will be injected from each gate. 

Fill Settings

Co-Injection requires special setup with regards to Fill Settings. Procedure

Open a part. Mesh the model with solid elements. Set the plastic material and co-injection with nitrogen gas. Specify the gate locations and material percentage amounts. Set the Fill Settings. Run a Flow analysis. Analyze the results. 1

230

Open a part file. Open Bathroom Handle from the Lesson16\Case Study folder.

SOLIDWORKS Simulation

Lesson 16 Gas Assistance Molding

2

Mesh the model.

Click Solid

.

Specify Non-Orthogonal Voxel, Hexahedral elements. Use all other default parameters. Click OK

.

Gas Assist

Plastic parts are designed to be thin in order to reduce cooling times, reduce warping and limit the amount of plastic used. However, there are instances when a plastic part must be thick. In these cases, gas assisted injection molding can be a solution. In gas assisted injection molding, resin is injected into the cavity so that it is about half full. Gas is then injected into the partially filled mold. Once resin comes into contact with the walls of the cavity, it tends to stick; allowing the gas to stay in the center of the part. The gas is then used to pack the part during the packing stage. Nitrogen is often used as the gas because it does not react with most resins.

Material Selection

In the case of a gas assisted injection molding process, two materials must be specified for the same domain; one resin the other gas.This is accomplished through the Set Co-Injection command.

Where to Find It



3

PlasticsManager Tree: Material, Polymer, Set Co-Injection

Set first material.

Click Polymer

.

Click Sort by Family. Expand ABS and select Asahi Chemical / Stylac 120.

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Gas Assistance Molding

4

Set Co-Injection material.

Click Set Co-Injection

.

Click the drop down next to the Set Co-Injection command and click 2nd. This allows the second material to be specified. Expand GAS and select Others / Nitrogen. Click OK.

Note

Once the materials have been specified using Co-Injection, the Injection Location command is then used to specify how much of each material will be injected into the cavity. In our case, half the cavity will be filled with resin and half the cavity will be filled with nitrogen gas. This will be performed next.

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5

Specifying a 50% fill with ABS.

Click Injection Location

.

Scroll down to the bottom of the Injection Location PropertyManager.

Under 1st Material Injection Range, specify the fill range from 0 to 50. Specify a 7 mm Pointer Diameter. Select a location on the model to add the gate as indicated in the image below. Click Add Location.

6

Specify a 50% fill with Nitrogen. Under Injection System click the drop down and click 2.

Under 1st Material Injection Range, specify the fill range from 0 to 0. Under 2nd Material Injection Range, specify the fill range from 50 to 100. Specify a 7 mm Pointer Diameter and add the gate as indicated in the image below.

Click OK

.

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Gas Assistance Molding

In a true gas assisted injection molding operation, nitrogen is injected through the runner system. For the sake of expedience, a runner system was not modeled here.

Note

7

Fill Time.

Click Fill Settings

.

Specify a Fill Time of 7 seconds. Note that the Injection System can be specified at the top of the PropertyManager. There is also a Co-Injection section towards the bottom. Explore these options. Click OK 8

.

Flow.

Click Flow

.

The simulation takes approximately 30 minutes to run.

9

Fill Time. Click Fill Time.

Click Clip Plane Click Play

.

to animate the results.

From the animation, it is very difficult to see the nitrogen filling the cavity.

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Lesson 16 Gas Assistance Molding

10 2nd material Fill time. Click 2nd material Fill time.

This plot shows the nitrogen and how it is predicted to fill the cavity. 11 Animate 2nd material.

Click Isosurface Click Play

.

to animate the results.

The animation shows that for the first few seconds of fill, no nitrogen enters the cavity. Once the nitrogen does come in, it pushes the ABS material to the outer walls. 12 Save and close the file.

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Lesson 16 Gas Assistance Molding

236

SOLIDWORKS Simulation

Lesson 17 Cooling Analysis

Upon successful completion of this lesson, you will be able to: 

Understand the cooling process in the injection molding cycle.



Run a cooling analysis and interpret the results.

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Cooling Analysis

Cooling Analysis

This lesson focuses on how to accurately model cooling throughout the injection molding process by simulating the thermodynamic effects of cooling channels, baffles, bubblers and the mold.

Stages in the Process

The major stages in the process are listed below: 

Cooling Channels

Specify the cooling channels using an existing sketch and the Channel Design wizard. 

Virtual Mold A Virtual Mold needs to be defined in the Solid mesh in order to

perform a cooling analysis. 

Cooling model

There are four separate cooling models available. We will explore these models and run simulations with two of them. 

Cool Analysis

We will perform an Cool analysis and analyze the results. Procedure

Create cooling channels and a virtual mold. Define materials to the cavity, the mold and the cooling fluid. Specify the Cool Settings. Define the cooling model for the system. Run a Cool analysis and analyze the results. Create a new simulation with baffles and bubblers. Run an additional Cool analysis using a separate cooling model.

Important!

A Cooling Analysis can only be performed using the SOLIDWORKS Plastics Premium package or higher. SOLIDWORKS Plastics Premium functionality will be featured throughout the remainder of this course. 1

Open a part file. Open Cooling Analysis from the Lesson17\Case Study

folder. From the View drop-down, enable Sketches. Two sketches which will be used to model the cooling channels are now visible.

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Cooling

Cooling occurs throughout all stages of the injection molding process; from the fill stage through ejection. The rate of cooling has a significant effect on part dimensions and influences part defects. If a part can be cooled uniformly, the residual stress within the part can be reduced, thereby minimizing the risk of warpage and cracking. The cooling process starts when heat is transferred from the hot, liquid resin to the mold walls of the cavity. The heat is then conducted through the metal cavity to cooling channels. Pumped fluid (often water or oil) runs through the cooling channels convecting heat away from the mold. The positioning and properties of the mold material and cooling channels are, therefore, an important consideration in mold design.

Cooling Channels and Mold Bodies

So far, we have assumed that the mold walls stay at a constant temperature as specified by the Mold Temperature parameter in Fill Settings . However, the mold temperature is never constant; it changes with time and location. In order to accurately model the temperature of the walls of the cavity, the cooling channels and the mold bodies must also be modeled. There are two ways to model the mold and the cooling channels. First, they can be modeled using conventional SOLIDWORKS geometry then specified as cooling channels and molds through the Assign Domains command. The second way is to start with a sketch which follows the profile of the cooling channels then use the Runner and Cooling System Design and the Virtual Mold Generation features. These options allow the mold and the runner system to be created through the Solid Mesh PropertyManager. PlasticsManager: MESH, Solid, Manual select Runner and Cooling System Design and Virtual Mold Generation

Where to Find It

2

Solid mesh.

Click Solid

and Manual.

Click Runner and Cooling System Design. Click Virtual Mold Generation. Click Next

.

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Cooling Analysis

3

Channel Design.

Window select the two sketches. Enter 10 for D1 and D2. Enter 3 for the Number of Elements. Click Assign.

The cooling channels are displayed in blue. Click Next

.

The parameters specified in the

Note

Channel Design page set the initial mesh (similar to Surface Mesh) for the cooling

channels. 4

Virtual Mold. Under Based On, click Size.

Enter the following values:   

X: 160 Y: 130 Z: 330

Click Add and Next

240

.

SOLIDWORKS Simulation

Lesson 17 Cooling Analysis

5

Category.

The part cavity, the cooling channel and the mold are correctly listed on the Domains page. Click Next 6

.

Surface Mesh. Set the Cavity Triangle Size to 1.5mm and click Mesh.

Click Mold, set the Triangle Size to 15mm and click Mesh.

Note

The parameters specified in the Channel Design page set the Surface Mesh for the mold and the cavity. Click Next Click OK Click Next

.

on the Summary page. on the Mesh Editing page.

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Cooling Analysis

7

Solid Mesh Cooling Channels. Click Tetrahedral on the Solid Mesh page

and click Next

.

Click Advance. Set Ring Count (Na): to 4. Set Ring Cut Count (Nb): to 10. Set Length ratio (Lr): to 0.5. Click OK

8

.

Solid Mesh Mold and Cavity. Click Cavity/Insert/Runner, Hybrid and Create Mesh.

The cavity is now meshed with solid elements. Click Mold, Tetrahedral and Create Mesh. The mold is now meshed with solid elements.

The section plot shows the part cavity, the cooling channel and the mold meshed with solid elements. Click Next Click OK

242

and click Next

again.

to complete the mesh.

SOLIDWORKS Simulation

Lesson 17 Cooling Analysis

Coolant

Molds are cooled with a variety of fluids, including water, water/glycol mixtures and oil. In many cases, water is the ideal fluid to use because it is cheap and has a high specific heat which means that it can absorb a lot of energy without a large change in temperature. Coolant material is defined through the Coolant command.

Where to Find It



Mold

Heat is conducted from the cavity to the cooling channels through the mold. Therefore, the mold material heavily influences the thermal state of the system. Molds can be made of aluminum (for low cycle molds) or steel (for high cycle molds). The mold material is defined through the Mold command.

Where to Find It



9

PlasticsManager Tree: Material, Coolant

PlasticsManager Tree: Material, Mold

Polymer.

Click Polymer

.

Search for and select SABIC Innovative Plastics CYCOLAC 28818E. Click OK. 10 Coolant.

Click Coolant Click Water. Click OK.

.

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Cooling Analysis

11 Mold. . Click Mold Click Steel - 420SS. Click OK.

Cool Settings

The Cool Settings control the relevant thermal properties of the system. These parameters include: Melt Temperature, Air Temperature, Min. Coolant Temperature, Average Coolant Flow Rate and the Mold Open Time. The Melt Temperature is the temperature of the resin when the cool simulation starts. When Flow or Flow + Pack results are present, the part temperature can be read from the result file. This will be covered in Cool on page 247. Min Coolant Temperature is the initial temperature of the coolant in each channel. The Average Coolant Flow Rate is the parameter which is used to specify the flow rate of coolant through the system. The flow rate should be high enough to achieve turbulence through the pipes because heat transfer increases significantly with turbulent flow. The Mold Open Time is the amount of time that the mold remains open while the part is being ejected. When the Eject Temperature is specified, the cooling time is assumed to be unknown and is solved for during the simulation.

Where to Find It

244



PlasticsManager Tree: Expand Process Parameters and doubleclick Cool Settings

SOLIDWORKS Simulation

Lesson 17 Cooling Analysis

12 Cool settings.

Click Cool Settings

.

Enter the following values:      

Inlet melt Temperature - 250°C Min Coolant Temperature - 25°C Air temperature - 25°C Average Coolant flow rate - 200 cc/s Mold Open Time - 5 sec Eject Temperature - 100°C

Click OK

Cooling Simulations

.

There are four models available for solving Cool simulations; Cool Flow Field, Cool Pipe, Cool Entrance and Mold Wall Temperature. Only one model can be active in a simulation. If more than one model is setup, the highest priority model is used.

Cool Flow Field

The Cool Flow Field model is the highest priority model and is also regarded as the most accurate and computationally demanding. The Cool Flow Field model solves for the fluid flow within the cooling lines using a fully three dimensional CFD (computational fluid dynamics) approach. Multiple inlets and outlets can be solved for using this model.

Where to Find It



PlasticsManager: Expand Boundary Conditions and click Cool Flow Field

Cool Pipe

The Cool Pipe model is the second highest priority model and is regarded as the second most accurate and computational demanding. The Cool Pipe model solves for the fluid flow using a more simplified method than the Cool Flow Field model. In order to use the Cool Pipe model, the channels must first be created from sketches using the Runner and Cooling System Design command. In this model, a single inlet and outlet must be defined.

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Cooling Analysis

Where to Find It



PlasticsManager: Expand Boundary Conditions and click Cool Pipe

Coolant Entrance

The Cool Entrance model is the third highest priority model. This model does not directly solve for the fluid moving through the channels. Rather, it models the heat transfer by determining the affective convection load from the inlet temperature and the flow rate of the cooling fluid.

Where to Find It



PlasticsManager: Expand Boundary Conditions and click Cool Entrance

Mold Wall Temperature

The Mold Wall Temperature model is the lowest priority model. This model is used to define the temperature of the mold wall at the cavity. Cooling lines are not directly solved for with this model.

Where to Find It



PlasticsManager: Expand Boundary Conditions and click Mold Wall Temperature

13 Coolant Flow Field Pipe 1.

Click Cool Flow Field . Click the drop down under Gravity Downward Directions and click +Z.

Click Pipe 1 from the list. Specify the following parameters:  

Flow rate - 200 cc/s Inlet Temperature - 25°C

Click Apply. Click Set Inlet and Outlet. Click Inlet and select the elements on the end of the pipe as shown in the image below. Click Select. Click Outlet and select the elements at the end of the pipe as shown in the image below. Click Select.

Outlet

246

Pipe 1

Inlet

SOLIDWORKS Simulation

Lesson 17 Cooling Analysis

14 Coolant Flow Field Pipe 2.

Follow a similar process, using the same parameters as specified in step 13 on page 246 for Pipe 2. Define inlet and outlet conditions for Pipe 2 as shown in the image below.

Click OK

.

Cool Analysis

As stated earlier, resin begins to cool as soon as it touches the mold walls and continues to cool through ejection. Depending on the sequence of the analyses which are performed (Cool, Fill, etc.), data can be exchanged between solvers.

Cool

When a Cool analysis is performed first, it is assumed that the cavity is initially filled with resin at Melt Temperature (as specified in Cool Settings ). If a Flow analysis is then performed, the thermal settings from the Cool analysis will be used as input for the Fill analysis. However, if a Fill analysis is performed first, the thermal settings from the Fill analysis will be used as input for the Cool analysis. Therefore, a final analysis should be run in this order: Flow --> Cool --> Flow --> Pack --> Warp

Where to Find It

PlasticsManager: Expand RUN and double-click Cool

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Cooling Analysis

15 Cool.

Click Cool

.

Note

The analysis takes 50 minutes to run.

Cool Results

The Cool Results include:         

Note

Part Cooling Time Cycle Averaged Temperature Temperature at End of Cooling Cycle Averaged Part Temperature Part Temperature at End of Cooling Cycle Averaged Mold Temperature Mold Temperature at End of Cooling Cycle Averaged Heat Flux Cycle Heat Loading

The term End of Cooling refers to a result as measured just before ejection. The term Cycle Averaged refers to a result which has been averaged over the entire time in the mold. PlasticsManager: Expand RESULTS and click Cool Results 16 Cool Results.

Disable Mold Visibility

and

Cooling Channel Visibility

from

the CommandManager. Click Cool Results

.

Click Part Cooling Time. Click Clipping Plane Mode. The maximum cooling time is about 18 sec at the thicker sections.

The cooling time could be reduced by making the walls thinner or by drawing more heat from the thicker regions.

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17 Temperature at End of Cooling. Click Temperature at End of Cooling.

Click Isosurface to 100. Min

and set the

The areas displayed have a temperature higher than the recommended part ejection temperature. Minimizing the thickness of these two areas will reduce the overall cooling time and consequently, the manufacturing cycle time. 18 Heat flux. Click Cycle Averaged Heat Flux and enable Cooling Channel Visibility

Note

.

The image shows where the channels are drawing the most thermal energy out of the system which can be useful if the channels need to be redesigned. Click OK

.

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Cooling Analysis

19 Heat removed from cooling channel. Expand Open Report Text File.

Click Cool Text. Scroll down to the bottom to locate Cooling stage results summary.

20 Save and close the file.

Baffle

250

A Baffle is a special type of Cooling Channel where the cooling fluid is channeled closer to the cavity. This allows a localized region of a cavity to be cooled at a higher rate.

SOLIDWORKS Simulation

Lesson 17 Cooling Analysis

Bubbler

This type of cooling channel is similar to a Baffle, but is actually two differently sized diameter channels, one inside the other. The smaller diameter inner channel is slightly shorter than the wider outer channel. The cooling medium will typically be pumped up through the inner channel and then spray outward into the top of the outer channel. The cooling medium then flows downward in between the outer and the inner channels, exiting when it reaches the bottom where it rejoins the primary cooling channel.

21 Open part file. Open Bubblers baffles from the Lesson17\Case Study

folder. From the View drop-down, enable Sketches. Two sketches which will be used to model the cooling channels are now visible. This is the same model geometry as Cooling Analysis but with new cooling line sketches. 22 Solid Mesh.

Click Solid

and Manual.

Click Runner and Cooling System Design. Click Virtual Mold Generation. Click Next

.

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Cooling Analysis

23 Baffles. Under Channel Parameters click Baffle.

Under D1 click 10. Click the sketch entity as shown in the image below and click Assign.

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24 Bubbler. Under Channel Parameters click Bubbler.

Under D1 click 12 and under D2 click 8. Click the sketch entity as shown in the image below and click Assign.

25 Cooling Channels. Under Channel Parameters click General.

Specify 10 mm cooling channels with 3 element segments for the remainder of the sketch entities.

Click Next

.

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Cooling Analysis

26 Setup Simulation. Follow step 4 on page 240 through step 12 on page 245 to setup the

simulation. 27 Cool Pipe.

Click Cool Pipe

.

Click Pipe 1 under Selections. Click Inlet Temperature and enter 25 °C. Click Flow rate enter 200 cc/s. Click Apply. Click Pipe 2 under Selections. Click Inlet Temperature and enter 25 °C. Click Flow rate enter 200 cc/s. Click Apply. If the direction of the flow is not as shown in the image below, select the pipe and click Reverse Flow. Click OK

.

28 Run the Simulation (Optional).

Click Cool

254

.

SOLIDWORKS Simulation

Lesson 17 Cooling Analysis

29 Results.

Analyze the results.

30 Save and close the file.

255

Exercise 13

SOLIDWORKS Simulation

Cooling Analysis

Exercise 13: Cooling Analysis

Calculate the cooling times for a part simulated using the Cool Entrance method for part cooling. This lab uses the following skills:  

Cooling Simulations on page 245 Cool Results on page 248

Units: Metric

Procedure

Follow the procedure below. 1

Open a part file. Open Cool Entrance from the Lesson17\Exercises folder.

This is the same model from the first part of Lesson 17: Cooling Analysis. We will use the Coolant Entrance model to simulate cooling with this part. 2

Review the simulation.

The simulation has already been partially setup following steps 2: Solid mesh. through 12: Cool settings. of the Lesson 17: Cooling Analysis lesson. Review the setup. 3

Cool Entrance. Click Cool Entrance.

Under Inlet Temperature enter 25 °C. Under Flow rate enter 200 cc/s. Click Select through. Windows select all the elements on the screen. Click Apply. Click OK. 4

Run analysis. Run a Cool analysis.

5

Results.

Compare the solution time and results to those obtained in step 16: Cool Results. on page 248. Is the improved accuracy in results achieved using the Coolant Flow Field method worth the increase in solution time in this case?

256

Lesson 18 Warpage Analysis

Upon successful completion of this lesson, you will be able to: 

Understand shrinkage and warpage of an injection molded plastic part.



Run a warpage analysis and interpret the results.

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Lesson 18

SOLIDWORKS Simulation

Warpage Analysis

Warpage Analysis

This lesson follows the process of analyzing a part to see how much it is predicted to warp after it is ejected from the mold. Excessive shrinking and warping may lead to undesirable dimensions of the final part.

Stages in the Process

The major stages in the process are listed below: 

Insert, Cooling Channel, Mold and Runner Systems

A solid mesh will be created on a part with an insert, cooling channels, a mold and a runner system. 

Cooling, Flow, Pack and Warp analysis

The simulation will be setup and run to analyze the part using the Cool, Fill, Pack and Warp solvers.

Procedure

Mesh the part with solid elements. Specify Fill, Pack, Cool, and Warp settings. Specify cooling using the Cool Entrance model. Run a Cool+Flow+Pack+Warp analysis. Analyze the part and determine how warping could be reduced. 1

Open a part file. Open Warp Analysis from the Lesson18\Case Study folder.

Activate the 3-Insert_Warp_start configuration. It includes an insert, and a runner system modeled as solid features. The cooling channels are currently modeled as sketches.

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2

Solid mesh.

Click Solid

, Manual.

Click Runner and Cooling System Design. Click Virtual Mold Generation. Click Next 3

.

Cooling Channels. Assign the following Cooling Channel parameters on the two

sketches as shown:    

Cooling Channel type: General D1: 10 mm D2: 10 mm Number of Elements: 4

Click Next 4

.

Mold Size. Click Based On and click Coordinate.

Specify the following parameters:   

X-Direction Bounds: -225 ~ 225 Y-Direction Bounds: -50 ~ 75 Z-Direction Bounds: -100 ~ 150

Click Add. Click Next

.

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Warpage Analysis

5

Domains. Apply the appropriate domains to each of the bodies. There should be a Cavity, a Runner, an Insert, a Cooling Channel and a Mold Domain.

Click Next 6

.

Mesh Control. Click Assign Size.

Specify a .5 mm mesh to the four faces of the gate and the single face at the split line where the cavity and the gate meet. Use the Mold Visibility making the selections.

Click OK 260

.

and Runner Visibility

commands when

SOLIDWORKS Simulation

Lesson 18 Warpage Analysis

7

Shell Mesh. Mesh the Cavity, Insert and Runner domains with a Triangle Size set to 2 mm.

Click Mesh. Click Mold. Set the Triangle Size to 15 mm. Click Mesh.

Click Next

.

Proceed to the Solid Mesh page. 8

Solid Mesh Cooling Channels. Click Tetrahedral.

Click Next

.

Click Advance. Mesh the Cooling Channels with the following parameters:   

Ring Count: 3 Ring cut count: 6 Length ratio: .5

Click OK

.

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Warpage Analysis

9

Solid Mesh. Click Cavity/Insert/Runner.

Click Hybrid. Click Create Mesh. Click Mold. Click Tetrahedral. Click Create Mesh. Click Next

.

Complete the mesh using default parameters. 10 Materials. Set the Materials as shown below: 

Polymer



Coolant



Mold



Insert

- PA6- BASF / ULTRAMID B3EG6 - Water - Steel - 420SS - Metal, Other Alloys - Magnesium Alloy

11 Fill and pack settings.

Set the following fill and pack settings options: 

Fill Settings

, Filling Time - 4 sec



Fill Settings

, Melt Temperature - 260 °C



Fill Settings

, Injection Pressure Limit - 150 MPa



Pack Settings

, Pressure Holding Time - 8 sec

12 Insert settings.

Click Insert Settings  

and specify the following parameters:

Insert Part Initial Temperature - 25°C Mold Wall Temperature - 90°C

Click OK

.

13 Cool Settings.

Click Cool Settings

.

Click Air Temperature and enter 25 °C. Click OK

262

.

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Lesson 18 Warpage Analysis

14 Coolant Entrance.

Click Coolant Entrance

.

Click Select through. Window select the entire cooling system. Use the default parameters and click Apply. Click OK

.

Shrinkage

Shrinkage is inherent in the injection molding process. It occurs because the mold is filled with hot resin under high pressures and then cools to room temperature. This reduction in temperature can cause the molded plastic part to shrink by as much as 20%, depending on material. See Lesson 9: Packing and Cooling Times for more details.

Reducing Shrinkage

There are several ways to reduce shrinkage, including:     

Warpage

Shrinkage is a contributing factor for part warpage. However, warpage is more complicated. Parts warp because of the combination of in-mold residual stress and nonuniform shrinkage. (If a part shrinks uniformly, as opposed to non-uniformly, it will not warp but become smaller instead.) The factors which contribute to warpage, include:   

Warp Settings

Increasing Packing Time Increasing Packing Pressure Decreasing barrel temperature Decreasing coolant temperature Increasing cooling time

Variation of temperature as the part cools in the mold Variation of pressure of the melt in the mold Variable rates of shrinkage dependent on molecular and fiber orientation

The Warp Settings specify the conditions of the part at ejection. Ambient Temperature is the environmental temperature the part

experiences after it is ejected from the mold. Gravity Direction is the direction in which the part would be dropped

from the mold. Where to Find It

PlasticsManager: Expand INPUT, Process Parameters and doubleclick Warp Settings

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Warpage Analysis

15 Warp settings.

Click Warp Settings following:  

and specify the

Ambient Temperature = 25°C Gravity Direction = -Y dir

Click OK

.

16 Injection Location.

Click Injection Location

.

Specify a 11 mm Pointer Diameter at the end of the sprue as shown. Click OK

.

17 Cool+Flow+Pack+Warp.

Click Cool+Flow+Pack+Warp

.

Three simulations will run starting with a Cool analysis, moving onto a Flow+Pack analysis, followed by a Warp analysis. The simulations should take approximately 2 hours to run.

Warp Results

The Warp Results include:



Total Stress Displacement In-mold Residual Stress Displacement Quenching Thermal Stress Displacement Total Stress Displacement (without fiber) Sink-Mark Profile In-mold Residual Von Mises Stress De-Molding Residual Von Mises Stress



PlasticsManager: Expand RESULTS and double-click

     

Where to Find It

Warp Results

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SOLIDWORKS Simulation

Lesson 18 Warpage Analysis

18 Total Stress Displacement.

Click Warp Results

.

Click Total Stress Displacement.

Note

This plot shows the total amount the part is predicted to warp after if comes out of the mold and cools to room temperature (25 °C). Keep in mind that this is a self equilibrated system (meaning, there are no restraints). Therefore, this plot as is may show different values when run on a separate system. This is to be expected.

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Warpage Analysis

19 Set Reference. Click Set Reference.

Click Based on plane. Click First Reference. Select the node on the vertex of the fillet as shown. Click Apply. Follow the same process for the Second Reference and Third Reference as shown.

Note

266

The plot now shows a zero displacement location (First Reference).

SOLIDWORKS Simulation

Lesson 18 Warpage Analysis

20 Deformation Scale. Click Deformation Scale and set the value to 10.

The shape the part takes as it warps is now obvious. Set the Deformation Scale back to 1.

Reducing and Fixing Warped Parts

As mentioned as mentioned in Warpage on page 263, there are several contributing factors for what makes a part warp. These factors will be analyzed systematically.

Thermal Contributions to Warping

There are two thermal contributions for warpage. First, is nonuniform part cooling. Second is the dependence of the thermal expansion coefficient on the molecule and fiber orientation. The Quenching Thermal Stress Displacement plot and the Total Stress Displacement (without fiber) plot can be used to isolate the contributions of these effects.

Typical Warp Shapes

There are three typical shapes a part can take as it warps.

Witch Hat

Chip

Taco

Witch Hat

This shape occurs when there is higher shrinkage on the outside of the part.

Chip

This shape occurs when there is higher shrinkage at the center of the part.

Taco

This shape occurs when there is higher shrinkage on one side of the part.

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Warpage Analysis

21 Quenching Thermal Stress Displacement. Click Quenching Thermal Stress Displacement.

Note

268

This plot shows the contribution of warpage due to temperature differences. These displacements appear to be significant - 1.4 mm max compared to 1.9 mm of Total Stress Displacement fixed at the References shown.

SOLIDWORKS Simulation

Lesson 18 Warpage Analysis

22 Pack Results.

Click Pack Results Packing.

and click Volumetric Shrinkage at End of

Set the Min to 7.5 and click Isosurface Mode.

Note

The region in blue indicates areas that will shrink more than 7.5%. Remember, a part will warp when it shrinks at an uneven rate. Predicting the direction of warp can also be analyzed by examining how a part cools. Hotter regions of a part will shrink at a higher rate, causing the part to warp into the direction of higher temperature.

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Warpage Analysis

23 Total Stress Displacement (without fiber).

Click Warp Results

.

Click Total Stress Displacement (without fiber).

This plot shows that without the contributions to fiber orientation, the part warps even further.

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24 Flow Results.

Click Flow Results

.

Click Fill Time then click Fiber Orientation. Move the Vector Number slider and the Vector Length slider to the middle.

Note

For BASF / ULTRAMID B3EG6 the thermal expansion coefficient parallel to the fiber orientation is 2.25e-005 1/°C and 6.67e-005 1/°C normal to fiber orientation.

Residual Stress

The filling and packing stages of the injection molding process occur under very high pressures. As the part cools, and is eventually ejected, these pressures can have a significant effect on part warpage.

Minimizing residual stress

The process conditions and design factors that reduce shear stress during cavity filling will help to reduce flow-induced residual stress. In general, the following factors lower the residual stresses:     

Longer fill time Shorter flow path Uniform wall thickness Uniform cooling of all surfaces Higher material and mold temperature

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Warpage Analysis

25 In-Mold Stress.

Click Warp Results

.

Click In-mold Residual Stress Displacement.

This plot shows the amount of displacement which is due to in-molded stress.

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SOLIDWORKS Simulation

Lesson 18 Warpage Analysis

26 De-Molding Residual Von Mises Stress. Click De-Molding Residual Von Mises Stress.

This plot shows the stress which remains in the part after it is ejected from the mold (de-molded).

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Lesson 18

SOLIDWORKS Simulation

Warpage Analysis

27 Sink-Mark Profile. Click Sink-Mark Profile.

The sink mark results from warp analyses take into account the in-mold stress as well as the out-of-mold cooling stress. The sink mark profile obtained from warp analysis is, therefore, more realistic than the prediction from flow analysis. 28 Save and close the file.

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Index

A adviser 27 air trap 118 analysis flow 22 B Baffle 250 Batch Manager 53 Birefringence 143 Bubbler 251 C cavity hide and show 217 Clamp Force Limit 168 Clamping Force 168 colors images in manual 4 configurations 41 Cool Flow Field 245 Cool Pipe 245 Cool Results 248 Cool Settings 244 Coolant 243 Coolant Entrance 246 Copying Settings 52 D design change 41, 42 Design Changes 41 Domain Order 223 Duplicate Study 51 F File Management 52 G Gas Assist 231 gate add automatically 65 multiple 157 Gate Blush 134 Glass Transition Temperature 83

I input material 18 Insert 211 insert hide and show 217 Inserts 213 Isosurface Mode 147 J Jetting 151 M material 18 Material Properties 80 Materials 18 Melt Temperature 83 mesh surface element 15 Mesh Editing 97 mode plastics to modeling 41 Mold 243 Mold Temperature 83 Mold Wall Temperature 246 P Packing and Cooling 140 Part Ejection Temperature 83 Product 81 PVT Data 86 R Race-tracking 118 Reaction Injection Molding 205 Resin Properties 82 results adviser 27 air trap 118 animate 25 dieseling effect 118 ease of fill 28 fill time 24, 38, 43 flow 23 flow front central temperature 39

pack 143, 248, 264 race-tracking 118 report text file 38 short shot 39 sink marks 68 volume shrinkage at packing end 145 weld lines 26 run analysis 22 runner balancing 176 cross-section 164 runner-balancing 176 S Shear Stress 134 short shot 34 Shrinkage 263 SolidWorks editing 42 Specific Heat 84 surface mesh 15 Symmetry Face 194 T Thermal Conductivity 84 Thermal Expansion Coefficient 87 thermoset plastics 205 Triangle Size 16 U User-defined Database 81 V Venting 122 Viscosity 85 W Warpage 263 X X-Y Plot 143

275

Index

276

SOLIDWORKS Simulation