Maintenance Management: Abhinav Kumar BFT/14/884 [PDF]

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Maintenance Management

Abhinav Kumar BFT/14/884

Q1) What should be the objectives of maintenance management for successful working of the maintenance department? The maintenance systems have all the same end objective: “Mission-ready machinery and equipment at minimum cost.” This end objective can be touched using different ways. 

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Some systems try to keep working machinery and equipments under the pressure of production. These systems have as single objective to rapidly restore the equipment to its operational readiness state using available resources. Another’s systems have the same main objective but this main objective is associate with another’s as: improve maintenance operations, reduce the amount and frequency of maintenance, reduce the effect of complexity, reduce the maintenance skills required, reduce the amount of supply support, establish optimum frequency and extent of preventive maintenance to be carried out, improve and ensure maximum utilization of maintenance facilities, and improve the maintenance organization. For understanding the most used maintenance systems (fig. 1):

A generic process for maintenance management consists of the following sequential management steps for successful working of maintenance department: 1. Asset maintenance planning: - Identify the asset; - Prioritize the asset according to maintenance strategy; - Identify its performance requirements according to strategy; - Evaluate the asset’s current performance; - Plan for its maintenance;

Maintenance task analysis determines the specific information and resources for each item that requires maintenance including:         

Description of the maintenance task (with the level of detail required for a skilled maintenance person); Frequency of the task (based on a relevant measure such as elapsed time, operating hours, number of operational cycles or distance); Number of personnel, skill level and time required to perform the task; Maintenance procedures for disassembly and reassembly; Safety procedures to be followed; Procedures for handling, transportation and disposal of hazardous materials; Special tools, test equipment and support equipment required; Spare parts, materials and consumables to be used or replaced; Observations and measurements to be made;

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Checkout procedures to verify proper operation and successful completion of the maintenance task.

2. Schedule maintenance operations; Scheduling for specific maintenance tasks needs to be done with enough time to schedule and supply the necessary resources. This includes:        

Identifying and assigning personnel; Acquiring materials and spare parts from external sources or inventory; Ensuring that tools, transportation, lifting and support equipment are available; Preparing required operating, maintenance, safety and environmental procedures and work plans; Identifying and reserving external resources; Identifying communication resources; Providing necessary training. Manage maintenance actions execution (including data gathering and processing);

3. Assess maintenance; The purpose of maintenance-related measurement is to measure the effectiveness of maintenance and maintenance support. Measurements related to specific equipment or groups of similar equipment may include: • Availability, reliability and maintainability; • Downtime or outage time; • Mean time between failure; • Mean repair time; • Time to failure, statistical representation such as Weibull analysis [16]; • Planned and unplanned maintenance cost; Measurement related to general maintenance management may consist of: • Proportion of planned vs unplanned tasks; • Planned work not completed on time; • Variation of resources between planned and actual; • Spare parts availability; • Workforce utilization and skill level; Assessment of preventive and corrective maintenance tasks can be performed either each time maintenance is done (such as after a major failure) or on a periodic basis to review overall performance, e.g. by type of equipment for a certain time period. 4. Ensure continuous improvement; Improvement in maintenance and maintenance support activities is achieved by management support, effective processes and communication. Improvement to maintenance and maintenance support can be achieved by changes in: Maintenance definition (type, line of maintenance, etc., for the equipment); 

Level of maintenance;

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Maintenance procedures; Skills and training of maintenance and operations personnel; Spare parts and materials; Tools and support equipment; Use of external resources; Operating procedures and conditions; Safety and environmental procedures; Equipment and system design; Maintainability of the equipment.

A validation process may be needed to ensure that the appropriate corrective or preventive action has been taken and improvement has been achieved. 5. Consider the possibility of equipment re-design. Modifications to equipment, whether to improve functionality or maintainability, should result in reassessment of maintenance and maintenance support. This may result in changes in maintenance definition, resources, training and associated documentation. Documentation issued by manufacturers, such as vendor service bulletins, should be carefully reviewed for changes to maintenance and maintenance support. Modifications to a system may result in some spare parts becoming redundant. For this reason care should be taken not to buy too large a quantity of spares. A modification may also apply to spare parts in store. A modification may require the provision of new materials and spare parts. The modification process should be supported by the configuration management system or some other change management system to ensure that changes to maintenance and maintenance support resulting from modifications are implemented and recorded through the proper configuration control procedures. Modifications should be evaluated to ensure there is no negative impact on maintenance and maintenance support.

Bathtub Curve The initial infant mortality period of bathtub curve is characterized by high failure rate followed by a period of decreasing failure. Many of the failures associated with this region are linked to poor design, poor installation, or misapplication. The infant mortality period is followed by a nearly constant failure rate period known as useful life.

Q2) Show the classification of maintenance system.

Maintenance

Planned Maintenance (PROACTIVE)

Predictive Maintenance

Statistical Based

Condition Based

Unplanned Maintenance (Reactive)

Preventive Maintenance

Running

Shutdown

Corrective Maintenance

Emergency

Deferred

Breakdown

Scheduled Maintenance

Remedial

Replace

Condition Based Maintenance

Shutdown Corrective

Reliability Based Maintenance

 Reactive Maintenance: Reactive maintenance is basically the “run it till it breaks” maintenance mode. No actions or efforts are taken to maintain the equipment as the designer originally intended to ensure design life is reached. Studies as recent as the winter of 2000 indicate this is still the predominant mode of maintenance in the United States. The referenced study breaks down the average maintenance program as follows: • >55% Reactive • 31% Preventive • 12% Predictive • 2% Other. Note that more than 55% of maintenance resources and activities of an average facility are still reactive.

 Preventive Maintenance Actions performed on a time- or machine-run-based schedule that detect, preclude, or mitigate degradation of a component or system with the aim of sustaining or extending its useful life through controlling degradation to an acceptable level.

 While preventive maintenance is not the optimum maintenance program, it does have several advantages over that of a purely reactive program.  By performing the preventive maintenance as the equipment designer envisioned, we will extend the life of the equipment closer to design. This translates into dollar savings.  Preventive maintenance (lubrication, filter change, etc.) will generally run the equipment more efficiently resulting in dollar savings. While we will not prevent equipment catastrophic failures, we will decrease the number of failures.  Minimizing failures translate into maintenance and capital cost savings.

 Predictive Maintenance Measurements that detect the onset of system degradation (lower functional state), thereby allowing causal stressors to be eliminated or controlled prior to any significant deterioration in the component physical state. Results indicate current and future functional capability.

 The advantages of predictive maintenance are many. A well-orchestrated predictive maintenance program will all but eliminate catastrophic equipment failures. We will be able to schedule maintenance activities to minimize or delete overtime cost. We will be able to minimize inventory and order parts, as required, well ahead of time to support the downstream maintenance needs. We can optimize the operation of the equipment, saving energy cost and increasing plant reliability.  Past studies have estimated that a properly functioning predictive maintenance program can provide a savings of 8% to 12% over a program utilizing preventive maintenance alone. Depending on a facility’s reliance on reactive maintenance and material condition, it could easily recognize savings opportunities exceeding 30% to 40%.  In fact, independent surveys indicate the following industrial average savings resultant from initiation of a functional predictive maintenance program:     

Return on investment: 10 times Reduction in maintenance costs: 25% to 30% Elimination of breakdowns: 70% to 75% Reduction in downtime: 35% to 45% Increase in production: 20% to 25%.

 Reliability Centered Maintenance Reliability centered maintenance (RCM) magazine provides the following definition of RCM: “a process used to determine the maintenance requirements of any physical asset in its operating context.”

 Basically, RCM methodology deals with some key issues not dealt with by other maintenance programs. It recognizes that all equipment in a facility is not of equal importance to either the process or facility safety. It recognizes that equipment design and operation differs and that different equipment will have a higher probability to undergo failures from different degradation mechanisms than others. It also approaches the structuring of a maintenance program recognizing that a facility does not have unlimited financial and personnel resources and that the use of both need to be prioritized and optimized.  In a nutshell, RCM is a systematic approach to evaluate a facility’s equipment and resources to best mate the two and result in a high degree of facility reliability and cost-effectiveness.  RCM is highly reliant on predictive maintenance but also recognizes that maintenance activities on equipment that is inexpensive and unimportant to facility reliability may best be left to a reactive maintenance approach.  The following maintenance program breakdowns of continually top-performing facilities would echo the RCM approach to utilize all available maintenance approaches with the predominant methodology being predictive. 