International Standard: IS0 System of Limits and Fits - Bases of Tolerances, Deviations and Fits [PDF]

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INTERNATIONAL

STANDARD

IS0 286-l First edition 1988-09-H

INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEXAYHAPOAHAR OPrAHM3A~MR IlO CTAHAAPTM3AlJMM

IS0 system

of limits

Part 1: Bases of tolerances, Systhme IS0 de tokrances

and fits

deviations

et d’ajustements

Partie 1: Base des tokrances,

-

and fits

-

&arts et ajustements

Reference number --``,````,``,,,`,``,`,,``,``,``,-`-`,,`,,`,`,,`---

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Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. They are approved in accordance with IS0 procedures requiring at least 75 % approval by the member bodies voting, This part of IS0 286 has been prepared by ISO/TC 3, Limits and fits, and, together with IS0 286-2, completes the revision of ISO/R 286, /SO system of limits and fits. ISO/R 266 was first published in 1962 and subsequently confirmed in November 1964; it was based on ISA Bulletin 25 first published in 1940. The major changes incorporated

in this part of IS0 266 are as follows :

a1 The presentation of the information has been modified so that IS0 286 can be used directly in both the design office and the workshop. This has been achieved by separating the material dealing with the bases of the system, and the calculated values of standard tolerances and fundamental deviations, from the tables giving specific limits of the most commonly used tolerances and deviations. b) The new symbols js and JS replace the former symbols j, and Js (i.e. s and S are no longer placed as subscripts) to facilitate the use of the symbols on equipment with limited character sets, e.g. computer graphics. The letters “s” and “S” stand for “symmetrical deviation”. c) Standard tolerances and fundamental deviations have been included for basic sizes from 566 to 3 156 mm as standard requirements (these were previously included on an experimental basis only). Two additional standard tolerance grades, IT17 and IT18, have been included.

e) Standard tolerance grades IT01 and IT0 have been deleted from the main body of this part of IS0 286, although information on these grades is given in annex A for users who may have a requirement for such grades. f)

Inch values have been deleted.

g) The principles, terminology by contemporary technology.

and symbols have been aligned with those required

Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated.

0

International Organization for Standardization,

1999 0

Printed in Switzerland

ii

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d)

IS0

286-l

Contents Introduction

: 1988 {El

Page ........................................................

Scope ............................................................. Field of application

..................................................

References ......................................................... Terms and definitions.

...............................................

Symbols, designation and interpretation of tolerances, and fits ............................................................

deviations

.............................................

9

..............................................

10

6

Graphical representation

7

Reference temperature,

8

Standardtolerancesforbasicsizesupto3

9

Fundamental

deviations for basic sizes up to 3 150 mm ...................

10

IO

Bibliography.

.......................................................

16

A

Bases of the IS0 system of limits and fits ...............................

17

B

Examples of the use of IS0 286-l ......................................

23

C

Equivalent terms ...................................................

24

.....................

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150 mm..

Annexes

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6

... Ill

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INTERNATIONAL

STANDARD

IS0 system

IS0 266-l : 1966 (E)

of limits and fits -

Part I : Bases of tolerances,

0

deviations

Introduction

and fits

2

Field of application

The need for limits and fits for machined workpieces was brought about mainly by the inherent inaccuracy of manufacturing methods, coupled with the fact that “exactness” of size was found to be unnecessary for most workpieces. In order that function could be satisfied, it was found sufficient to manufacture a given workpiece so that its size lay within two permissible limits, i.e. a tolerance, this being the variation in size acceptable in manufacture.

The IS0 system of limits and fits provides a system tolerances and deviations suitable for plain workpieces.

Similarly, where a specific fit condition is required between mating workpieces, it is necessary to ascribe an allowance, either positive or negative, to the basic size to achieve the required clearance or interference, i.e. a “deviation”.

In particular, the general term “hole” or “shaft” can be taken as referring to the space contained by (or containing) the two parallel faces (or tangent planes) of any workpiece, such as the width of a slot or the thickness of a key.

With developments in industry and international trade, it became necessary to develop formal systems of limits and fits, firstly at the industrial level, then at the national level and later at the international level.

The system also provides for fits between mating cylindrical features or fits between workpieces having features with parallel faces, such as the fit between a key and keyway, etc.

This International Standard therefore gives the internationally accepted system of limits and fits. Annexes A and B give the basic formulae and rules necessary for establishing the system, and examples in the use of the standard are to be regarded as an integral part of the standard.

For simplicity and also because of the importance of cylindrical workpieces of circular section, only these are referred to explicitly. It should be clearly understood, however, that the tolerances and deviations given in this International Standard equally apply to workpieces of other than circular section.

NOTE - It should be noted that the system is not intended to provide fits for workpieces with features having other than simple geometric forms. For the purposes of this part of IS0 286, a simple geometric form consists of a cylindrical surface area or two parallel planes.

3 Annex C gives a list of equivalent terms used in IS0 286 and other International Standards on tolerances.

References

NOTE -

See also clause 10.

IS0 1, Standard measurements.

1

Scope

This part of IS0 286 gives the bases of the IS0 system of limits and fits together with the calculated values of the standard tolerances and fundamental deviations. These values shall be taken as authoritative for the application of the system (see also clause A. I). This part of IS0 286 also gives terms and definitions together with associated symbols.

1)

of

reference

temperature

for industrial

length

IS0 286-2, IS0 system of limits and fits - Part 2: Tables of standard tolerance grades and limit deviations for holes and shafts. ISOIR 1938, IS0 system of limits and fits - Inspection of plain workpieces. 1) IS0 8615, Technical principle.

drawings

-

Fundamental

tolerancing

At present under revision.

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IS0

4

286-l

Terms

: 1988 (E)

and definitions

For the purposes of this International Standard, the following terms and definitions apply. It should be noted, however, that some of the terms are defined in a more restricted sense than in common usage.

4.5 zero line : In a graphical representation of limits and fits, the straight line, representing the basic size, to which the deviations and tolerances are referred (see figure 1). According to convention, the zero line is drawn horizontally, with positive deviations shown above and negative deviations below (see figure 2).

4.1

shaft: A term used, according to convention, to describe an external feature of a workpiece, including features which are not cylindrical (see also clause 2).

4.1.1 basic shaft: Shaft chosen as a basis for a shaft-basis system of fits (see also 4.11,1). For the purposes of the IS0 system of limits and fits, a shaft the upper deviation of which is zero.

4.2

hole : A term used, according to convention, to describe an internal feature of a workpiece, including features which are not cylindrical (see also clause 2). --``,````,``,,,`,``,`,,``,``,``,-`-`,,`,,`,`,,`---

4.2.1 basic hole: Hole chosen as a basis for a hole-basis system of fits (see also 4.11.2). For the purposes of the IS0 system of limits and fits, a hole the lower deviation of which is zero.

4.3

size: A number expressing, in a particular numerical value of a linear dimension.

unit, the

4.3.1 basic size; nominal size: The size from which the limits of size are derived by the application of the upper and lower deviations (see figure 1). NOTE - The basic size can be a whole number or a decimal number, e.g. 32; 15; 8,75; 0,5; etc.

4.3.2 actual measurement.

size:

The

size of a feature,

obtained

by

4.3.2.1 actual local size: Any individual distance at any cross-section of a feature, i.e. any size measured between any two opposite points. 4.3.3 limits of size: The two extreme permissible sizes of a feature, between which the actual size should lie, the limits of size being included, 4.3.3.1 maximum limit of size: size of a feature (see figure 1).

The greatest permissible

4.3.3,2 minimum limit of size : The smallest permissible size of a feature (see figure 1). 4.4 limit system deviations.

: A system of standardized tolerances and

Figure 1 -

Basic size, and maximum limits of size

4.6 deviation: The algebraic difference between a size (actual size, limit of size, etc.) and the corresponding basic size. NOTE - Symbols for shaft deviations are lower case letters (es, ei) and symbols for hole deviations are upper case letters L!CS, EI) (see figure 2).

4.6.1

limit deviations

: Upper deviation and lower deviation.

4.6.1.1 upper deviation (ES, es): The algebraic difference between the maximum limit of size and the corresponding basic size (see figure 2). 4.6.1.2 lower deviation (EZ, ei): The algebraic difference between the minimum limit of size and the corresponding basic size (see figure 2). 4.6.2 fundamental deviation : For the purposes of the IS0 system of limits and fits, that deviation which defines the position of the tolerance zone in relation to the zero line (see figure 2). NOTE - This may be either the upper or lower deviation, but, according to convention, the fundamental deviation is the one nearest the zero line.

4.7 size tolerance: The difference between the maximum limit of size and the minimum limit of size, i.e. the difference between the upper deviation and the lower deviation. NOTE - The tolerance is an absolute value without sign.

2

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and minimum

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IS0 266-l

: 1966 (E)

Lower deviation (,!?I, ei) (4.6.1.2) Clearance (4.8) r

Tolerance zone (4.7.3)

Figure 3 Figure 2 -

Conventional tolerance

representation zone

Clearance

of a

4.7.1 standard tolerance (IT) : For the purposes of the IS0 system of limits and fits, any tolerance belonging to this system. NOTE - The letters of the symbol IT stand for “international Tolerance” grade. 4.7.2 standard tolerance grades: For the purposes of the IS0 system of limits and fits, a group of tolerances (e.g. IT7), considered as corresponding to the same level of accuracy for all basic sizes. 4.7.3 tolerance zone: In a graphical representation of tolerances, the zone, contained between two lines representing the maximum and minimum limits of size, defined by the magnitude of the tolerance and its position relative to the zero line (see figure 2).

4.8.1 minimum clearance: In a clearance fit, the positive difference between the minimum limit of size of the hole and the maximum limit of size of the shaft (see figure 4). 4.8.2 maximum clearance: In a clearance or transition fit, the positive difference between the maximum limit of size of the hole and the minimum limit of size of the shaft (see figures 4 and 5).

4.9

interference : The negative difference between the sizes of the hole and the shaft, before assembly, when the diameter of the shaft is larger than the diameter of the hole (see figure 6). 4.9.1 minimum interference: In an interference fit, the negative difference, before assembly, between the maximum limit of size of the hole and the minimum limit of size of the shaft (see figure 7).

4.7.4 tolerance class: The term used for a combination of fundamental deviation and a tolerance grade, e.g. h9, D13, etc. 4.7.5 standard tolerance factor (i, II the IS0 system of limits and fits, a factor the basic size, and which is used as a nation of the standard tolerances of the

: For the purposes of which is a function of basis for the determisystem.

NOTES 1 The standard tolerance factor i is applied to basic sizes less than or equal to 500 mm. 2 The standard tolerance factor lis applied to basic sizes greater than 600 mm.

4.8

clearance : The positive difference between the sizes of the hole and the shaft, before assembly, when the diameter of the shaft is smaller than the diameter of the hole (see figure 3).

Figure 4 -

Clearance

fit

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IS0 286-l

: 1988 (I3

Maximum clearance

Maximum interference -

-

(4.8.2)

L

interference (4.9.2)

Figure 5 - Transition

r

Figure 7 -

J

fit

Minimum interference

-

Interference

fit

4.10.1 clearance fit: A fit that always provides a clearance between the hole and shaft when assembled, i.e. the minimum size of the hole is either greater than or, in the extreme case, equal to the maximum size of the shaft (see figure 8).

Interference (4.9) Hole

HI-III?

line

Shaft

Figure 6 -

4.10.2

interference

interference

Figure 6 -

Interference

Schematic

between

representation

of clearance

fits

fit : A fit which everywhere provides an the hole and shaft when

assembled,

i.e.

the maximum size of the hole is either smaller than or, in the extreme case, equal to the minimum size of the shaft (see figure 9). Shaft

4.9.2 maximum interference: In an interference or transition fit, the negative difference, before assembly, between the minimum limit of size of the hole and the maximum limit of size of the shaft (see figures 5 and 7).

Shaft

4.10

fit: The relationship resulting from the difference, before assembly, between the sizes of the two features (the hole and the shaft) which are to be assembled. NOTE - The two mating parts of a fit have a common basic size.

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WA Hole

Figure 9 -

Schematic

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Zero line Hole

representation

of interference

fits

IS0 286-l

4.10.3 transition fit: A fit which may provide either a clearance or an interference between the hole and shaft when assembled, depending on the actual sizes of the hole and shaft, i.e. the tolerance zones of the hole and the shaft overlap completely or in part (see figure 10).

:I988

(E)

4.11.2 hole-basis system of fits: A system of fits in which the required clearances or interferences are obtained by associating shafts of various tolerance classes with holes of a single tolerance class. For the purposes of the IS0 system of limits and fits, a system of fits in which the minimum limit of size of the hole is identical to the basic size, i.e. the lower deviation is zero (see figure 12).

Zero line

Figure 10 - Schematic

representation

of transition

4.10.4 variation of a fit: The arithmetic sum tolerances of the two features comprising the fit.

fits

of the

NOTE - The variation of a fit is an absolute value without sign. 4.11 fit system: A system of fits comprising holes belonging to a limit system.

shafts and

4.11.1 shaft-basis system of fits: A system of fits in which the required clearances or interferences are obtained by associating holes of various tolerance classes with shafts of a single tolerance class. For the purposes of the IS0 system of limits and fits, a system of fits in which the maximum limit of size of the shaft is identical to the basic size, i.e. the upper deviation is zero (see figure 11).

I

Basic size (4.3.1)

NOTES 1 The horizontal continuous ations for holes or shafts.

lines represent the fundamental

devi-

2 The dashed lines represent the other limits and show the possibility of different combinations between holes and shafts, related to their grade of tolerance (e.g. H6/h6, H6/js5, H6/p4).

Figure 12 -

Hole-basis

system

of fits

4.12 maximum material limit (MML): The designation applied to that of the two limits of size which corresponds to the maximum material size for the feature, i.e.

- the maximum feature (shaft),

(upper) limit of size for an external

Shaft “h”

-

the minimum (lower) limit of size for an internal feature (hole). NOTE L-Basic size (4.3.1)

4.13 least material limit (LMLI : The designation applied to that of the two limits of size which corresponds to the minimum material size for the feature, i.e.

NOTES 1 The horizontal continuous ations for holes or shafts.

Previously called “GO limit”.

lines represent the fundamental

devi-

2 The dashed lines represent the other limits and show the possibility of different combinations between holes and shafts, related to their grade of tolerance (e.g. G7/h4, H6/h4, M5/h4).

Figure 11 - Shaft-basis

system

of fits

- the minimum (lower) limit of size for an external feature (shaft), - the maximum (upper) limit of size for an internal feature (hole). NOTE -

Previously called “NOT GO limit”.

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286-l

: 1988 (E)

5 Symbols, of tolerances, 5.1

designation deviations

and and

Examples :

interpretation fits

32H7 8Qjs15 10Og6 100 12%

Symbols

51.1

Standard

tolerance

grades

The standard tolerance grades are designated by the letters IT followed by a number, e.g. IT7. When the tolerance grade is associated with (a) letter(s) representing a fundamental deviation to form a tolerance class, the letters IT are omitted, e.g. h7. NOTE - The IS0 system provides for a total of 20 standard tolerance grades of which grades IT1 to IT18 are in general use and are given in the main body of the standard. Grades IT0 and ITOl, which are not in general use, are given in annex A for information purposes.

ATTENTION - In order to distinguish between holes and shafts when transmitting information on equipment with limited character sets, such as telex, the designation shall be prefixed by the following letters : -

H or h for holes;

-

S or s for shafts.

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IS0

Examp /es : 56H5 becomes H56H5 or h5Oh5 56h6 becomes S56H6 or s5Oh6

5.1.2 5.1.2.1

Deviations This method drawings.

Position of tolerance zone

The position of the tolerance zone with respect to the zero line, which is a function of the basic size, is designated by (an) upper case letter(s) for holes (A . . . ZCI or (a) lower case letter(s) for shafts (a . , . zc) (see figures 13 and 141. NOTE - To avoid confusion, I, i; L, I; 0,o;

5.1.2,2

the following

by the letters “ES”

for

Lower deviations by the letters “EZ” for

Tolerance

be

used

on

between

mating features shall be designated

the common

basic size;

b)

the tolerance

class symbol for the hole;

c)

the tolerance

class symbol for the shaft.

-

H or h for holes;

-

S or s for shafts;

-

and the basic size repeated.

Examples : 52H7/g6

becomes H52H7lS52G6

This method drawings.

Examples : l-t7 (holes) h7 (shafts) Toleranced

or 52 z

ATTENTION - In order to distinguish between the hole and the shaft when transmitting information on equipment with limited character sets, such as telex, the designation shall be prefixed by the following letters :

class

A tolerance class shall be designated by the letter(s) representing the fundamental deviation followed by the number representing the standard tolerance grade.

5.2.2

not

a)

52H7/g6

Designation

5.2.1

shall

Upper deviations

The lower deviations are designated holes and the letters “ei” for shafts.

5.2

letters are not used:

designation

Fit

A fit requirement by

Q, q; W, w.

The upper deviations are designated holes and the letters “es” for shafts. 5.1.2.3

5.2.3

of

5.3 size

A toleranced size shall be designated by the basic size followed by the designation of the required tolerance class, or the explicit deviations.

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5.3.1

of

Interpretation Tolerance

designation

or h52h7ls52g6 shall

not

of a toleranced indication

in accordance

be

used

on

size with

IS0 5615

The tolerances for workpieces manufactured to drawings marked with the notation, Tolerancing IS0 8015, shall be interpreted as indicated in 5.3.1.1 and 5.3.1.2.

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IS0 286-I : 1983 (E)

a)

b)

Holes (internal featurt?s)

Shafts (external features)

NOTES 1

According

to convention,

2

For details concerning

the fundamental fundamental

Figure

13 -

deviation

deviations

Schematic

for J/j,

is the one defining K/k, M/m

representation

the nearest limit to the zero line.

and N/n, see figure 14.

of the positions

of fundamental

deviations

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7

k

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IS0 266-l

5.3.1.1

6

Linear size tolerances

A linear size tolerance controls only the actual local sizes (twopoint measurements) of a feature, but not its form deviations (for example circularity and straightness deviations of a cylindrical feature or flatness deviations of parallel surfaces). There is no control of the geometrical interrelationship of individual features by the size tolerances. (For further information, see ISO/R 1936 and IS0 6615.) 5.3.1.2

Graphical

: 1966 (E)

representation

The major terms and definitions given in clause 4 are illustrated in figure 15. In practice, a schematic diagram such as that shown in figure 16 is used for simplicity. In this diagram, the axis of the workpiece, which is not shown in the figure, according to convention always lies below the diagram. In the example illustrated, the two deviations of the hole are positive and those of the shaft are negative.

Envelope requirement

Single features, whether a cylinder, or established by two parallel planes, having the function of a fit between mating parts, are indicated on the drawing by the symbol @ in addition to the dimension and tolerance. This indicates a mutual dependence of size and form which requires that the envelope of perfect form for the feature at maximum material size shall not be violated, (For further information, see ISO/R 1936 and IS0 8015.1

Upper deviation (4.6.1 .l) Lower deviation (4.6.1.2) -

NOTE - Some national standards (which should be referred to on the drawing) specify that the envelope requirement for single features is the norm and therefore this is not indicated separately on the drawing.

5.3.2 Tolerance IS0 6015

indication

not in accordance

with

The tolerances for workpieces manufactured to drawings which do not have the notation, Tolerancing IS0 8015, shall be interpreted in the following ways within the stipulated length : a)

For holes

The diameter of the largest perfect imaginary cylinder, which can be inscribed within the hole so that it just contacts the highest points of the surface, should not be smaller than the maximum material limit of size. The maximum diameter at any position in the hole shall not exceed the least material limit of size.

Minimum limit of size (4.3.3.21

For shafts

The diameter of the smallest perfect imaginary cylinder, which can be circumscribed about the shaft so that it just contacts the highest points of the surface, should not be larger than the maximum material limit of size. The minimum diameter at any position on the shaft shall be not less than the least material limit of size.

Basic size (4.3.1)

Figure 15 -

Graphical

representation

Hole

The interpretations given in a) and b) mean that if a workpiece is everywhere at its maximum material limit, that workpiece should be perfectly round and straight, i.e. a perfect cylinder.

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Maximum limit of size (4.3.3.1)

b)

Unless otherwise specified, and subject to the above requirements, departures from a perfect cylinder may reach the full value of the diameter tolerance specified. For further information, see ISO/R 1936. NOTE - In special cases, the maximum form deviations permitted by the interpretations given in a) and b) may be too large to allow satisfactory functioning of the assembled parts: in such cases, separate tolerances should be given for the form, e.g. separate tolerances on circularity and/or straightness (see IS0 1101).

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Figure 16 - Simplified

schematic

diagram

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IS0 286-l

7

:I988

Reference

(El

9.2

temperature

Fundamental

deviations

for holes

[except deviation JS (see 9.311 The temperature at which the dimensions of the IS0 system of limits and fits are specified is 20 “C (see IS0 I).

8 Standard 3150mm 8.1

tolerances

for basic

sizes

up to

The fundamental deviations for holes and their respective sign ( + or - 1 are shown in figure 18. Values for the fundamental deviations are given in table 3. The upper deviation (ES) and lower deviation (EZ) are established from the fundamental deviation and the standard tolerance grade (IT) as shown in figure 18.

Basis of the system

8.2

Values of standard

tolerance

Deviations K to ZC (not valid for tolerance grades less than or equal to IT8 of deviation K and tolerance class M8)

Deviations A to H

The bases for calculating the standard tolerances are given in annex A.

grades (IT)

Values of standard tolerance grades IT1 to IT18 inclusive are given in table 1. These values are to be taken as authoritative for the application of the system.

Zero line

h Y

e

NOTE - Values for standard tolerance grades IT0 and IT01 are given in annex A.

deviations

9.1

deviations

Fundamental

for basic

sizes

up

EI = positive (+I fundamental deviation

ES = negative ( - 1 fundamental deviation

ES = EI + IT

EI = ES - IT

for shafts

[except deviation js (see 9.311

Figure 16 -

The fundamental deviations for shafts and their respective sign (+ or - ) are shown in figure 17. Values for the fundamental deviations are given in table 2. The upper deviation (es) and lower deviation (ei) are established from the fundamental deviation and the standard tolerance grade (IT) as shown in figure 17.

I

Deviations a to h

9.3

Fundamental

Deviations

deviations

for holes

js and JS

(see figure 19) The information given in 9.1 and 9.2 does not apply to fundamental deviations js and JS, which are a symmetrical distribution of the standard tolerance grade about the zero line, i.e. for js:

Deviations k to zc L

and for JS :

A

es = negative ( -1 fundamental deviation ei = es - IT

Figure 17 -

Zeroline 4

ei = positive ( + 1 funda-

I I

Deviations

I j

mental deviation

LIT 2

es = ei + IT

for shafts

Figure 19 -

10

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Hole

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Deviations

js and JS

--``,````,``,,,`,``,`,,``,``,``,-`-`,,`,,`,`,,`---

9 Fundamental to3150mm

IS0 286-I

9.4

Fundamental

The information of the standard

deviations

j and J

given in 9.1 to 9.3 does not apply to fundamental deviations j and J, which are, for the most part, asymmetrical tolerance grade about the zero line (see IS0 286-2, tables 8 and 24).

Table 1 - Numerical

r

Basic size

Above

values of standard

tolerance

IT321

IT421 1 IT521 1 IT6

IT7

IT8

up to and in-

distributions

grades IT for basic sizes up to 3 160 mm’)

Standard

I IT121 IT221

mm

: 1988 (EI

tolerance

grades

IT9 1 IT10 1 IT11 1 IT12 1 IT13 1 IT143)I IT153q ITI63)

IT173)j ITl83)

Tolerances

400 !a0

6302)

9

11

16

22

32

44

70

110

175

260

440

0,7

630

6002)

10

13

18

25

36

50

60

125

200

320

500

0,8 9

I,1

1.75

2,8

4,4

7

11

1.25 1,4

2

3.2

5

8

12,5

2,3

3,6

5,6

9

14

1)

Values for standard tolerance grades IT01 and IT0 for basic sizes less than or equal to 500 m m are given in annex A, table 5.

2)

Values for standard tolerance grades IT1 to IT5 (incl.) for basic sizes over 506 m m are included for experimental use.

3)

Standard tolerance grades IT14 to IT18 6ncl.J shall not be used for basic sizes less than or equal to 1 mm.

--``,````,``,,,`,``,`,,``,``,``,-`-`,,`,,`,`,,`---

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IS0 266-l

: 1966 (E)

Table

2 -

Numerical

values

of the

Fundamental Basic size

Upper deviation

es

mm All standard

-I-

up to and including

Above -

3’)

at) -

bl)

270

-140

C

cd

-60

-34

tolerance

--``,````,``,,,`,``,`,,``,``,``,-`-`,,`,,`,`,,`---

60 =I=

I

I

-

120

120

140

250

I

280

260

1

315

1)

!m 560

630

630

710

710

800

IT71

IT8

1

20

I-161

I

100

100

-1

1-210

-1251

I-621

-1951

I-961

-10

0

-12

0

-14

0

-15

0

-17

0

-32

0

560

800

900

9cQ

1000

lOOil

1 120

im

1 250

I

;;I

d

-321 I

grades

1250

1400

1400

16cCl

1600

1600

1600

2WO

2066

2 240

2240

2506

-290

I I

I

I

1

I

I

I

!

I

I

I

!

I -3m

I

l-3=

!

-220 1

-110

I

I

I

l-40

-240

-120

-460

-260

-130

I

I

I

I

I

I

I

1 -520

-290

-145

1

Fundamental deviations a and b shall not be used for basic sizes less than or equal to 1 mm.

2)

-1 -34

0

-38

0

For tolerance classes js7 to jsll, if the IT value number, n, is an odd number, this may be rounded to the even number immediately below, so that the ITtl resulting deviations, i.e. f , can be expressed in whole micrometres. 2

12

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IS0 266-l

fundamental

deviations

: 1966 (E)

of shafts Fundamental deviation values in micrometres

values Lower deviation

IT4

I77

Up to IT3 (incl.) and above IT7 k

0I

ei

T

All standard

m

n

r

P

0

+2

+

4

+

+I

0

+4

+

8

+ 12

+I

0

+6

+ 10

+ 16

+I

0

+7

+ 12

+ 18

+2

0

+8

+ 15

+2

0

+9

+ 17

+ 26

+2

0

+11

+ 20

+ 32

+3

0

+13

+ 23

+ 37

t

S

U

0

+15

0

+17

+ 31

0

+20

+34

+4

0

+21

+ 37

0

+23

+ 40

0

0

+26

+44

0

0

+30

+ 50

0

0

+34

+66

0

0

+40

+643

OI 0

I 0

0

0 0

+ 60

+ 62 _+6&l

+120

+46

+ 78

+140

+66

+ 62

+I70

+66

+110

+195

~ 0

+76

Z

V

za

zb

zc

I 1141+

1441+1721+2101+ 170

254

+

525

I +202 I +246 I+ 300I+

+ 27

-l-4

+5

X

701+81l+971+

1 + 66 I+ +4

V

grades

6

+ 63 +3

tolerance

+135

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+240

+ 60 1 +

106 1 +

146 1 +

130 1 +

180

+

210 1 +262 1 +310 258

+310

+385

1+

3

-I- 470

196

+

264 1 +340 1 +425

t-

269

+

390

+475

S-590

+

+

294

+

435

+530

+660

-I- 620

232

+

33

+

252

+

36-O +

490 I +595 I +740 640 +660 t620

+

620

+

780

+I160

+

660

+

640

+I300

+300

+

640

+

960

+330

+

720

+I050

+1690

+370

+

620

+1200

+1650

+400

+

920

+I350

+2000

4-440

+I000

+I500

+2300

+460

-f-1100

+1650

+2500

+550

+I250

+1900

+29cxl

+660

+I400

+2100

+3200

+ 64

+

140

+

+106

+

190

+114

-I- 208

+I26

+

+I32

+

+250 +260

l-

1+

740 1 +

+

730

+

900

+lOQO

920 1 +I 100 +lOOO i-1250

1+

!

520 1 +

+1150

+1 5m I+1900

I+l.100 . -

1 +I650

1 +2100

+I450

+I650

+2400

+I600

+2100

+2600

+1450

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--``,````,``,,,`,``,`,,``,``,``,-`-`,,`,,`,`,,`---

deviation

13

286-l

: 1988 (E)

Table

3 -

Numerical

I I

Fundamental

Basic size

of the

deviation

EI

Lower deviation All standard

tolerance

F EF r-10 t 6 t14

+ 10

~18 -

+ 13

II IT6

grades

Above

3 6 10 14 16 24 30 40 60 86 60

values

IT7

IT6

f=G -

G

H

t4 t6 t8 -

+2 +4 t5

0 0 0

+2 -t5 t5

t4 -

+6

+6 t8

+10

-1 +A

t12

t6

0

t6

t10

+7

0

+8

t9

0

+10

+ 16

JS2)

--``,````,``,,,`,``,`,,``,``,``,-`-`,,`,,`,`,,`---

IS0

J 0

0

-1 +A

-2 - 4tA - 8+A

-2 -4 - 6

t15

-1 +A

- 7tA

- 7

t12

+26

-, 2tA

- 8tA

- 8

+10

+14

t24

-2+A

-9+A

-9

0

+13

t18

t28

-2+A

-11 +A

-11

t12

0

+16

+22

+34

-3tA

-13+A

-13

+14

0

t18

+26

l-15+41

-15

t15

0

t17

0

ii8

0

t20

0

+22

0

+24

0

t26

0

+20

-40

t

50

+ 320 +180

+130

65

+

+190

+I40

80

+ 350 +200

t150

310 340

+170

tm

100

+

380

+220

+170

120

+

410

t240

+180

140

t

460 +260

+ 25 -

t200 -3+A

1

1

-

225 250 280 315

355

I

260 280

+ 820 +420 + 920 +4so

+280 +m

315

t1050

+540

+330

-l-600

+360

+680

+403

355

400

1 +1m +135O

+190

i-110 -

+210

+125

+ 62 -

+ 76 -

-

-

-

-

-

01

001

1 I

l-28 0

01

l-30 0

0

i-32 0

01 I

-

0

0

t3a

0

01

I-34 I

II

I-40

I -48

I

t34

-28 I

I

I

I-58 I

I

!

-88

-

-

I)

I

-76

I

Fundamental deviations A and B shall not be used for basic sizes less than or equal to 1 mm.

2)

For tolerance classes JS7 to JSll, if the IT value number, n, is an odd number, this may be rounded to the even number immediately below, so that the ITn resulting deviations, i.e. f ?, can be expressed in whole micrometres.

3) For determining the values K, M and N for standard tolerance grades up to IT8 (inch) and deviations P to ZC for standard tolerance grades up to IT7 (incl.), take the A values from the columns on the right.

14

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IS0 286-l

fundamental

deviations

: 1988 (E)

of holes Fundamental deviation values in micrometres

values er deviation

Values for A

ES

u/-z (incl.)

Standard P

-4

- 8+A -lO+A -12+A

R

S

-

-

6

-

10

-

0

-

12

-

15

-

19

-

0

-

15

-

19

-

23

-

-

18

14

-23-

grades above IT7

lulvlxlYl

T

-4

0

tolerance

-

28

2

-

22

-29

-

35.

-

-

-17-!-A

-

-26

-34

43--

-

-

-23+A

4l-

IT: IT4

T5 IT6i I T7

TI

0 1 i--

b yi i-i I

0

a s ?-

1 -

2

118

1,E -

2 -

3

--

1,:

3 -

4

ZA

ZB

-

20

23

-

28

28

-34 -40

-

!3J-

64

-45

-

60-

JJ

J388-

18

33 -39

-15+A

Standard tolerance grades

41

-47

-!3-

48

-55

-64

46- a

60 I -68

54 -

JO -81

I

-

-a-

26

-

32

-

35

-

42

-

42

-

52

-

I

- 97

-

63J5-

I ZC

98

94-112-149 -.~ 1 I - 136 -

114

180

0

13 2

3

3

3

0 T 6-

9

7

-

8

12 -

9 -

14 -

4 5

32

2 -

3 -

5

6

11 -

16 -

- 37

2 -

4 -

5

7

13 -

19 -

6201- 800 JKII900 3 J80-loo0 -

4

6

7

15

23

-

-27-!-A

-

5ml-

670

-3l+A

-

6801-1150

-

9601-1250

-10%

I-1

350

-

-

3

4

6

9

17

26

-

-

-

-

-34+A

4 -

4 -

7

9

m -

29 -

-37-14

4 -

5 -

7

11

21 -

32 -

5 -

5 -

7

13

23 -

34 -

-

-

-

-

-

0

-4O+A -44 -50 -56 -66

-68

-1261-

- 78 -68

78

-100

-120

-136

490

-595

-740

-

360

-

540

-660

-820

-1000

450

3301-

920 -1100

-1450 -16M)

-1250

-150-260-400-603 -

310

-175

-

340 -

-

-

660

500 -

740

-

940

-140

-

430

-220

-

470 520 -

680 -1050 760 -1150

580 ~~~ I -

950

-260

I

-195 -240

-

-33Ol~~~ I

-370

- 170

I

-210

-300

I

-110

252

-155

-250

I

- 92

-

-185-380-560-940

I

-

232]-

-132

640

-

620

840 - -I -1m ---1460

72OI-1050~-l&M -~- I ---

-

820 -1200

-4al I--- I

9201-1.250 --- I ---

I

I

I

I

I

I

-

---

-

-

-

-

-

-

-

-

-

-

-

-

-

-1850

$

-2@3J

-440

-1cm

-1500

-7m ____

-460

-1lco

-1650

-2m

-550

-1250

-1900

-2900

-580

-1400

-2100

-3200

3) (conch.) Examples: K7 in the range 18 to 30 mm: A = 8 pm, therefore ES = -2 S6 in the range 18 to 30 mm: A = 4 pm, therefore ES = -35

-

-

-

-

-

-

f 8 = +6 pm + 4 = -31

pm

4)

Special cases : for tolerance class M6 in the range from 250 to 315 mm, ES = -9 pm (instead of - 11 urn).

5)

Fundamental deviation N for standard tolerance grades above IT8 shall not be used for basic sizes less than or equal to

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-

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mm.

15

--``,````,``,,,`,``,`,,``,``,``,-`-`,,`,,`,`,,`---

UP

IS0

266-I

: 1966 (EI

10

Bibliography

IS0 1947, System of cone tolerances for conical workpieces from C = 1 : 3 to 1 : 500 and lengths from 6 to 630 mm.

The following International Standards on tolerancing and tolerance systems will be useful with regard to the application of this part of IS0 286: IS0 406, Technical ances - Indications

drawings on drawings.

Linear and angular

IS0 2692, Technical drawings Maximum material principle.

toler-

IS0 1101, Technical drawings - Geometrical tolerancing Tolerancing of form, orientation, location and run-out Generalities, definitions, symbols, indications on drawings.

-

tolerancing

-

IS0 5166, System of cone fits for cones from C = 1 : 3 to 1 : 500, lengths from 6 to 630 mm and diameters up to 600 mm.

1) At present at the stage of draft. (Revision, in part, of IS0 2769 : 1973.)

16

Geometrical

IS0 271X-1, General tolerances for dimensions without tolerance indications - Part 1: Tolerances for linear and angular dimensions. 1)

IS0 1829, Selection of tolerance zones for general purposes.

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-

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is0

Annex

: 1988 (E)

A

Bases of the IS0 system --``,````,``,,,`,``,`,,``,``,``,-`-`,,`,,`,`,,`---

A.1

286-l

of limits

and fits

(This annex forms an integral part of the standard.)

General

A.2

This annex gives the bases of the IS0 system of limits and fits. The data are given primarily so that values can be calculated for fundamental deviations, which may be required in very special circumstances and which are not given in the tables, and also so that a more complete understanding of the system is provided.

4 -

size steps

For convenience, the standard tolerances and fundamental deviations are not calculated individually for each separate basic size, but for steps of the basic size as given in table 4. These steps are grouped into main steps and intermediate steps. The intermediate steps are only used in certain cases for calculating standard tolerances and fundamental deviations a to c and r to zc for shafts, and A to C and R to ZC for holes.

It is once more emphasized that the tabulated values in either this part of IS0 286 or IS0 286-2, for standard tolerances and fundamental deviations, are definitive, and shall be used when applying the system.

Table

Basic

The values of the standard tolerances and fundamental deviations for each basic size step are calculated from the

Basic

size steps

Values in millimetrc a)

Values in millimetres b)

Basic sizes up to 500 m m (incl.1

Basic sizes above 500 m m up to 3 150 m m (incl.)

No subdivision

I)

These are used, in certain cases, for deviations a to c and r to zc or A to C and R to ZC (see tables 2 and 3).

2)

These are used for the deviations r to

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u and R to U (see tables 2 and 3).

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17

IS0 286-l

: 1988 (E)

mean (D) of the extreme sizes (Dt and L&l of that

geometrical

step, as follows :

A.3.2 Derivation of standard tolerances basic sizes up to and including 500 mm A.3.2.1

For the first basic size step (less than or equal to 3 mm), the geometrical mean, D, according to convention, is taken between the sizes 1 and 3 mm, therefore D = 1,732 mm.

A.3

Standard

A-3.1

tolerance

Standard

grades

The IS0 system of limits and fits provides for tolerance grades designated ITOI, ITO, ITI, . . . size range from 0 up to 500 mm (incl.), and tolerance grades in the size range from 500 mm up (incl.1, designated IT1 to IT18.

Table 6 - Formulae for standard tolerances in grades ITOI, IT0 and ITI for basic sizes up to and including 500 mm

20 standard , IT18 in the 18 standard to 3 150 mm

As stated in the “Foreword”, the IS0 system is derived from ISA Bulletin 25, which only covered basic sizes up to 500 mm, and was mainly based on practical experience in industry. The system was not developed from a coherent mathematical base, and hence there are discontinuities in the system and differing formulae for the deviation of IT grades up to 500 mm. The values for standard tolerances for basic sizes from 500 mm up to 3 150 mm (incl.) were subsequently developed for experimental purposes, and since they have proved acceptable to industry they are now given as a part of the IS0 system. It should be noted that values for standard tolerances in grades IT0 and IT01 are not given in the main body of the standard because they have little use in practice; however, values for these are given in table 5.

Values in micrometres Formula Standard tolerance grade

I)

Numerical values for standard in grades IT01 and IT0

Standard tolerance grades

I IT01

Above

3 6 10 18 30 50 80 120 180 250 315 400

I

tolerances

Up to and including 3 6 10 18 30 50 80 120 180 250 315 400 500

I

IT0

Tolerances urn

I

0,3 OS4 0,4 0,5

‘33 W-3 W3 1

12 2 2,5 3 4

0,5

66 W3 023 1 1

12 I,5 2 3 4 5 6

where D is the geometric mean of the basic size in millimetres 0.3 + 0,008D

ITO’)

0,5 + 0,OlW

IT1

0,8 + 0,020D

See the “Foreword” and A.3.1.

A.3.2.2

Standard

tolerance

grades IT5 to IT18

The values for standard tolerances in grades IT5 to IT18 for basic sizes up to and including 500 mm are determined as a function of the standard tolerance factor, i. The standard tolerance factor, i, in micrometres, from the following formula :

is calculated

+ 0,OOlD

where D is the geometric mean of the basic size step in millimetres (see clause A-21. This formula was empirically derived, being based on various national practices and on the premise that, for the same manufacturing process, the relationship between the magnitude of the manufacturing errors and the basic size approximates a parabolic function. The values of the standard tolerances are calculated in terms of the standard tolerance factor, i, as shown in table 7. It should be noted that from IT6 upwards, the standard tolerances are multiplied by a factor of 10 at each fifth step. This rule applies to all standard tolerances and may be used to extrapolate values for IT grades above IT18.

Example : IT20 = IT15 x 10 = 640i x 10 = 6400i NOTE - The above rule applies except for IT6 in the basic size range from 3 to 6 mm (incl.).

--``,````,``,,,`,``,`,,``,``,``,-`-`,,`,,`,`,,`---

18

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for calculation

IT01 1)

i = 0,45 m

Basic size

grades IT01 to IT4

The values of standard tolerances in grades ITOI, IT0 and IT1 are calculated from the formulae given in table 6. It should be noted that no formulae are given for grades IT2, IT3 and IT4. The values for tolerances in these grades have been approximately scaled in geometrical progression between the values for IT1 and IT5.

General

Table 5 -

tolerance

(IT) for

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IS0 286-l

Table 7 Basic size mm

Formulae

for standard

tolerances

: 1988 (El

in grades IT1 to IT18

Standard tolerance grades ITll)

IT211 IT311 IT411

IT5

IT6

IT7

IT8

IT9

IT10

IT11

IT12

IT13

IT14

IT15

IT16

IT17

1OOOi 16ooi

IT18

up to Above

Formulae for standard tolerances (Results in micrometres)

and in-

eluding

5Qo

500 3150

-

-

-

-

7i

1Oi

l6i

25i

40i

64

1OOi 160i

250i

4COi

640i

21

2.71

3,71

51

71

101

16r

251

4OI

641

1001

2501

4001

6401 10001 16001 25031

1602

25GOi

1 I See A.3.2.1.

The values for standard tolerances in grades IT1 to IT18 are determined as a function of the standard tolerance factor, I. The standard tolerance factor, I, in micrometres, from the following formula :

is calculated

Table 8 -

Rounding for IT values up to and including standard tolerance grade IT11 Roundinn values in micrometres Basic size

Calculated values obtained from the formulae given in A.3.2 and A.3.3 +!I% Above

I = 0,004D + 2,l

Up to and including

0 60

where D is the geometric mean of the basic size step in millimetres (see clause A.2).

100 200 500 1000 2000 5Oao 1ocoo 20 000

The values of the standard tolerances are calculated in terms of the standard tolerance factor, Z, as shown in table 7. It should be noted that from IT6 upwards, the standard tolerances are multiplied by a factor of 10 at each fifth step. This rule applies to all standard tolerances and may be used to extrapolate values for IT grades above IT18.

/

Rounding

60 100 200 500 1000 2000 5000 10 000 20000 5oooo

3%JL

in multiples

1 1 5 10 -

--``,````,``,,,`,``,`,,``,``,``,-`-`,,`,,`,`,,`---

A.3.3 Derivation of standard tolerances UT1 for basic sizes from 500 mm up to and including 3 150 mm

of

1 2 5 10 20 50 100 200 500 1000

Example : NOTES

IT20 = IT15 x IO = 6491 x 10 = 64001

1 The formulae for standard tolerances in grades IT1 to IT5 are given on a provisional basis only. (These did not appear in ISO/R 286 : 1352.)

1 For the small values in particular, it has sometimes been necessary to depart from these rules, and, in some instances, even from the application of the formulae given in A.3.2 and A.3.3 in order to ensure better scaling. Therefore the values given for the standard tolerances in tables 1 and 5, as appropriate, shall be used in preference to calculated values when applying the IS0 system.

2 Although the formulae for i and Zvary, continuity of progression is assured for the transition range.

2 Values for standard tolerances in grades IT1 to IT18 are given in table 1 and for IT0 and IT01 in table 5.

A.3.4 Rounding tolerances

A.4

NOTES

of values

for standard

Derivation

deviations

deviations

For each basic size step, the values obtained from the formulae given in A.3.2 and A.3.3, for standard tolerances in grades up to and including ITII, are rounded off in accordance with the rules given in table 8.

A.4.1

The calculated values of standard tolerances in grades above IT1 1 do not require rounding off because they are derived from values of tolerance grades IT7 to IT1 1, which have already been rounded off.

The fundamental deviation given by the formulae in table 9 is, in principle, that corresponding to the limits closest to the zero line, i.e. the upper deviation for shafts a to h and the lower deviation for shafts k to zc.

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Fundamental

of fundamental

for shafts

The fundamental deviations for shafts are calculated from the formulae given in table 9.

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IS0 288-l

: 1988 (E)

Except for shafts j and js, for which, strictly speaking, there is no fundamental deviation, the value of the deviation is independent of the selected grade of tolerance (even if the formula includes a term involving ITnL

A.4.2

Fundamental

deviations

Hole-basis fit

Shaft-basis fit

(ei) + IT(n-I)= (ES) + ITn (ei)- ITn=(fS)- ITh-I)

for holes

The fundamental deviations for holes are calculated from the formulae given in table 9 and, therefore, the limit corresponding to the fundamental deviation for a hole is exactly symmetrical, in relation to the zero line, to the limit corresponding to the fundamental deviation for a shaft with the same letter. This rule applies to all fundamental following :

deviations except for the

a) deviation N, for standard tolerance grades IT9 to IT16 in basic sizes above 3 mm up to 500 mm (incl.), for which the fundamental deviation is zero; b) shaft or hole basis fits, for basic sizes above 3 up to 600 mm (incl.), in which a hole of a given standard tolerance grade is associated with a shaft of the next finer grade (e.g. H7/p6 and P7/h6), and which are required to have exactly the same clearance or interferences, see figure 20. In these cases, the fundamental deviation, as calculated, is adjusted by algebraically adding the value of d as follows :

ES = ES (as calculated) + d where d is the difference ITn - IT(n - 1) between the standard tolerance, for the basic size step in the given grade, and that in the next finer grade.

Example :

Figure 20 -

Diagrammatic representation given in A.4.2bl

of the rule

The fundamental deviation given by the formulae in table 9 is, in principle, that corresponding to the limits closest to the zero line, i.e. the lower deviation for holes A to H and the upper deviation for holes K to ZC. Except for holes J and JS, for which, strictly speaking, there is no fundamental deviation, the value of the deviation is independent of the selected grade of tolerance (even if the formula includes a term involving ITn).

For P7 in the basic size range from 18 up to 30 mm :

A = IT7 - IT6 = 21 - 13 = 8 pm NOTE - The rule given in b) above is only applicable for basic sizes over 3 m m for fundamental deviations K, M and N in standard tolerance grades up to and including IT8, and deviations P to ZC in standard tolerance grades up to and including IT7.

A.4.3 Rounding deviations

of values for fundamental

For each basic size step, the values obtained from the formulae given in table 9 are rounded off in accordance with the rules given in table 10.

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IS0 288-l

Table 9 Basic size mm

r

1 120 1

Fundamental deviation

Sign (negative

a

-

b

-

es

C

-

es

cd

-

es

3 150

d

-

es

3150

e

-

es

120 500 160 500 40 500

160

0 40

IO

lo

(

ef

0

3 150

is

0

5003) 3 150

k

500

0 500 0

for fundamental

Shafts

up to and including

Above

Formulae

Designation

pos~~ve~

/

-

es

A

EZ

+

B

EI

+

C

Geometric mean of the values for C, c and D, d

EI

+

1600.44 1 ID0141

EI EI

+ +

-+

es ei

+

ei

0,5 ITn

n

+

ei

50034 0,040 + 21

0

3 150

r

+

ei

0

50

50 24

3 150 3 156

S

+

ei

t

+

ei

1

U

+

ei

1 IT7 + D

I 1

V

ei

1 IT7 + 1,250

ei

1 IT7 + 1,6D

ei

1 IT7 + W

ei

1 IT7 + 2,5D

ei

1 IT8 + 3.150

18

I

500 I

0

1

0

I

500 500 500 5cil

0 0

1 I

I

X V

I

t

I

Z

za

+

+

I

+

I

+

I

IT7 + 0 to 5

0,07W + 37,8 Geometric mean of the values for P, p and S, s IT8 + 1 to 4 IT7 + 0,4D IT7 + 0,630

zb

+

ei

IT9 + 40

ZC

+

ei

IT10 + 50

-+

1

120

120

500

1

160

160 0 40

500 40 500

CD

0

10

D

0

E

0

3 150 3 150

1 1 1 1 t

K4)

No sian

ES

-

N4)

ES

-

P4)

ES

-

Fz4)

ES

-

s4)

ES ES ES ES ES ES ES ES ES

-

1 1 I 1 1

I

lo

I

0

3 150

0

500

5005) 3 150

0 500

500 3 150

0

500

500

3 150

0

3150

50 3150 3150 3150

u4)

1

0 50 24 0

V4)

1

14

I

500

X4) 1 Y4) I 24) ZA4) 1 ZB 41 zc 41

0

1

500

18

I

500

0 0 0 0

1 I

500 5oa 5-00 500

T4)

1 1 1 I 1 1

up to and inciuding

Above

JS

-

ES

Deviation = 0

ei

500 500

Ei

033G

+

I 1

pos%e)

+

P

14 0

Fundamental deviation

EI

5ca 3 150

3150

Sign (negative

Designation

265 + I,30 3,5D = 140 + 0,850 = 1,8D 5200.2 95 + 0,8D

500

1

Basic size mm

Holes

Formulael) where D is the geometric mean of the basic size in millimetres

(El

and holes

o

3150

0

for shafts

1

No sinn

5cMl

deviations

:I988

1

1)

Fundamental deviations (i.e. results from formulae) in micrometres.

2)

Values only given in tables 2 and 3.

3)

Formula only applies to grades IT4 to IT7 inclusively; fundamental deviation k for all other basic sizes and all other IT grades = 0.

4)

Special rule applies [see A.4.2bll.

5)

Formula only applies to grades up to IT8 inclusively; fundamental deviation K for all other basic sizes and all other IT grades = 0.

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IS0 286-l

: 1688 (E)

Table

10 -

Rounding

for fundamental

deviations Rounding values in micrometres Basic size above 509 m m up to 3 150 m m Encl.1

up to 590 m m Encl.1

Calculated values obtained from the formulae given in table 9

Fundamental

w

-I-

a to g A to G

deviations

k to zc KtoZC

d to u D to U

Above

Up to and including

5 45 50 loo 200 300 5ocl 550 500 800 1000 2oOa

45 50 100 200 300 500 550 500 800 1000 2ooo 5Gvo

. * .

* . *

. . .

20 x IOn 50 x 10” loo x 10”

50 x 10n loo x IOn 200 x 10n

1 x 10” 2 x 10” 5 x 10”

Rounding 1 2 5 5 10 10 10 20 20 20 50

1 1 1 2 2 5 5 5 IO 20 50 100

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in multiules

of 1 1 2 5 10 10 20 20 20 20 50 100

IS0 286-l

Annex Examples

: 1888 (E)

B

of the use of IS0 286-l

(This annex forms an integral part of the standard.)

B.l

6.3

General

Examples

This annex gives examples in the use of the IS0 system of limits and fits, in determining the limits for shafts and holes.

B.3.1 Determining 0 4Ogll

The numerical values of the upper and lower deviations for the more generally used basic size steps, fundamental deviations and tolerance grades have been calculated and are tabulated in IS0 286-2.

Basic size step : 30 to 50 mm (from table 4)

the limits

of size for a shaft

Standard tolerance = 160 pm (from table 1) Fundamental deviation = -9 pm (from table 2)

In special cases, not covered by IS0 286-2, the appropriate upper and lower deviations, and hence the limits of size, can be calculated from the data given in fables 1 to 3, and tables 4 to 6 in#annex A in this part of IS0 286.

Upper deviation = fundamental Lower deviation

deviation = -9 pm

= fundamental deviation - tolerance = -9 - 169pm = - 169pm

Limits of size :

B.2

Review

of special

features

A summary of the features and factors which shall be taken into consideration when using this part of IS0 286 to derive upper and lower deviations for special cases is given below: shafts and holes a, A, b, B are provided only for basic sizes greater than 1 mm; shafts j8 are provided only for basic sizes less than or equal to 3 mm; holes K in tolerance grades above IT8 are provided only for basic sizes less than or equal to 3 mm; shafts and holes t, T, v, V and y, Y are only provided for basic sizes greater than 24 mm, 14 mm and 18 mm, respectively (for smaller basic sizes, the deviations are practically the same as those of the adjacent tolerance grades) ; tolerance grades IT14 to IT18 are only provided for basic sizes greater than 1 mm; holes N of tolerance grades above IT8 are only provided for basic sizes greater than 1 mm.

Maximum

= 40 - 0,009 = 39,991 mm

Minimum

= 40 - 0,169 = 39,831 mm

8.3.2

Determining

the limits

of size for a hole

0 130N4 Basic size step : 120 to 180 mm (from table 4) Standard tolerance = 12 pm (from table I) Fundamental deviation = -27

+ d pm (from table 3)

Value of A = 4 pm (from table 3) Upper deviation = fundamental deviation = -27 + 4 = -23 pm Lower deviation = fundamental deviation - tolerance = -23 - 12 pm = -35 pm Limits of size: Maximum

= 130 - 0,023 = 129,977 mm

Minimum

= 130 - 0,035 = 129,965 mm

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IS0 296-l : 1998 (El

Annex Equivalent

C terms

(This annex does not form an integral part of the standard.)

C.l

General

This annex establishes a list of terms used in IS0 286 (and in other International

Standards

on tolerances).

NOTE - In addition to terms used in the three official IS0 languages (English, French and Russian), the equivalent terms in German, Spanish, Italian, Swedish and Japanese are also given. These have been included at the request of Technical Committee ISO/TC 3 and are published under the responsibility of the member bodies for Germany, F.R. (DIN), Spain (AENOR), Italy RJNI), Sweden (SIS) and Japan (JISCL

C.2

Notes on presentation

The numerals 01 to 90 give the alphabetical

order for the first language (i.e. English) only (for reference).

The column “Reference clause” refers to the number of the clause, sub-clause, important place) in this part of IS0 286. The words given in “parentheses”

indicate that the part of the term placed between them may be omitted.

Synonyms have been separated by a semi-colon. some of the preceding words. Short explanations

C.3

etc. in which the term is defined (or the most

Square brackets indicate that the word(s) placed between them may replace all or

as regards the term have been presented in note form.

Recommendations

for the user

It is recommended that the users, for convenience, accordingly on the left-hand side of the table,

re-arrange the vocabulary alphabetically

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in their own languages and number them

IS0 286-l : 1988 (EI

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ISO 286-l

: 1999 (El

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: 1666 (E)

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IS0 266-I

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: 1666 (E)

I

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I

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IS0 266-I

I

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:I988

E)

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1s0 266-l

I

:

I

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c

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IS0 286-l

: 1988 (El

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IS0

266-l

: 1666 (E)

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UDC

621.763.1/.2

Descriptors

: dimensional tolerances,

fits,

fundamental tolerances,

definitions,

symbols,

Price based on 30 pages

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designation,

schematic representation,

dimensions.