ISO Tolerance Part 1

INTERNATIONAL STANDARD

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

IS0 system of limits and fits -

Part 1: Bases of tolerances, deviations and fits

Systhme IS0 de tokrances et d’ajustements -

Partie 1: Base des tokrances, &arts et ajustements

IS0 286-l First edition 1988-09-H

Reference number

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Not for Resale, 05/21/2008 06:43:27 MDTNo reproduction or networking permitted without license from IHS

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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).

d) 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 and symbols have been aligned with those required by contemporary technology.

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

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IS0 286-l : 1988 {El

Contents Page

6

7

8

9

IO

Introduction ........................................................

Scope .............................................................

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

References .........................................................

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

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

Graphical representation .............................................

Reference temperature, ..............................................

Standardtolerancesforbasicsizesupto3 150 mm.. .....................

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

Bibliography. .......................................................

Annexes

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

6

9

10

10

10

16

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INTERNATIONAL STANDARD IS0 266-l : 1966 (E)

IS0 system of lim its and fits -

Part I : Bases of tolerances, deviations and fits

0 Introduction

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.

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”.

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.

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.

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

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.

2 Field of application

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

For simplicity and also because of the importance of cylindrical workpieces of circular section, only these are referred to ex- plicitly. 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.

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.

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.

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 References

NOTE - See also clause 10.

IS0 1, Standard reference temperature for industrial length measurements.

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 drawings - Fundamental tolerancing principle.

1) At present under revision.

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IS0 286-l : 1988 (E)

4 Terms 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 unit, the numerical value of a linear dimension. Figure 1 - Basic size, and maximum and minimum

limits of size

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).

4.6 deviation: The algebraic difference between a size (actual size, limit of size, etc.) and the corresponding basic size.

NOTE - The basic size can be a whole number or a decimal number, e.g. 32; 15; 8,75; 0,5; etc.

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).

4.3.2 actual size: The size of a feature, obtained by measurement.

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: The greatest permissible size of a feature (see figure 1).

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

4.4 limit system : A system of standardized tolerances and deviations.

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.



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IS0 266-l : 1966 (E)

Lower deviation (,!?I, ei) (4.6.1.2)

Tolerance zone (4.7.3)

Figure 2 - Conventional representation of a tolerance zone

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).

4.7.4 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 : For the purposes of the IS0 system of limits and fits, a factor which is a function of the basic size, and which is used as a basis for the determi- nation of the standard tolerances of the system.

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).

r Clearance (4.8)

Figure 3 - Clearance

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).

Figure 4 - Clearance fit



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IS0 286-l : 1988 (I3

Maximum clearance -

(4.8.2)

L interference J (4.9.2)

Figure 5 - Transition fit

r Interference (4.9)

Figure 6 - Interference

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).

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.

Maximum interference -

Minimum - interference

Figure 7 - 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).

HI-III? Hole

line

Shaft

Figure 6 - Schematic representation of clearance fits

4.10.2 interference fit : A fit which everywhere provides an interference between 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

Shaft

WA Zero line

Hole Hole

Figure 9 - Schematic representation of interference fits



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IS0 286-l :I988 (E)

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 com- pletely or in part (see figure 10).

Zero line

Figure 10 - Schematic representation of transition fits

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

NOTE - The variation of a fit is an absolute value without sign.

4.11 fit system: A system of fits comprising shafts and holes belonging to a limit system.

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).

Shaft “h”

L-Basic size (4.3.1)

NOTES

1 The horizontal continuous lines represent the fundamental deviations for holes or shafts.

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

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).

I Basic size (4.3.1)

NOTES

1 The horizontal continuous lines represent the fundamental deviations for holes or shafts.

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 (upper) limit of size for an external feature (shaft),

- the minimum (lower) limit of size for an internal feature (hole).

NOTE - Previously called “GO limit”.

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.

- 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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IS0 286-l : 1988 (E)

5 Symbols, designation and interpretation of tolerances, deviations and fits

5.1 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.

Examples :

32H7 8Qjs15 10Og6 100 12%

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.

Examp /es :

56H5 becomes H56H5 or h5Oh5 56h6 becomes S56H6 or s5Oh6

5.1.2 Deviations

5.1.2.1 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, the following letters are not used:

I, i; L, I; 0,o; Q, q; W, w.

5.1.2,2 Upper deviations

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

5.1.2.3 Lower deviations

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

5.2 Designation

5.2.1 Tolerance class

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

Examples :

l-t7 (holes) h7 (shafts)

5.2.2 Toleranced size

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

This method of designation shall not be used on drawings.

5.2.3 Fit

A fit requirement between mating features shall be designated by

a) the common basic size;

b) the tolerance class symbol for the hole;

c) the tolerance class symbol for the shaft.

52H7/g6 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 :

- H or h for holes;

- S or s for shafts;

- and the basic size repeated.

Examples :

52H7/g6 becomes H52H7lS52G6 or h52h7ls52g6

This method of designation shall not be used on drawings.

5.3 Interpretation of a toleranced size

5.3.1 Tolerance indication in accordance 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) Holes (internal featurt?s)

b) Shafts (external features)

NOTES

1 According to convention, the fundamental deviation is the one defining the nearest limit to the zero line.

2 For details concerning fundamental deviations for J/j, K/k, M/m and N/n, see figure 14.

Figure 13 - Schematic representation of the positions of fundamental deviations



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k



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IS0 266-l : 1966 (E)

5.3.1.1 Linear size tolerances 6 Graphical representation

A linear size tolerance controls only the actual local sizes (two- point 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.)

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.

5.3.1.2 Envelope requirement In the example illustrated, the two deviations of the hole are positive and those of the shaft are negative.

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 indication not in accordance with IS0 6015

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.

b) For shafts

Minimum limit of size (4.3.3.21

Maximum limit of size (4.3.3.1)

Basic size (4.3.1)

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.

Figure 15 - Graphical representation

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.

Hole

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 satisfac- tory 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).

Figure 16 - Simplified schematic diagram



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IS0 286-l :I988 (El

7 Reference temperature 9.2 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). 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.

8 Standard tolerances for basic sizes up to 3150mm

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.

8.1 Basis of the system

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

8.2 Values of standard tolerance 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.

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

Deviations A to H Deviations K to ZC (not valid for tolerance grades

less than or equal to IT8 of deviation K and tolerance

class M8)

Zero line h e Y

9 Fundamental deviations for basic sizes up to3150mm

9.1 Fundamental deviations for shafts [except deviation js (see 9.311

EI = positive (+I funda- ES = negative ( - 1 fundamental deviation mental deviation

ES = EI + IT EI = ES - IT

Figure 16 - Deviations for holes

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. 9.3 Fundamental deviations js and JS

(see figure 19) 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.

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 a to h I Deviations k to zc L

and for JS :

Zeroline A 4

es = negative ( -1 funda- I

ei = positive ( + 1 fundamental deviation mental deviation j

I Hole

ei = es - IT I es = ei + IT LIT

2 Figure 17 - Deviations for shafts Figure 19 - Deviations js and JS



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IS0 286-I : 1988 (EI

9.4 Fundamental deviations j and J

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

Table 1 - Numerical values of standard tolerance grades IT for basic sizes up to 3 160 mm’)

r Basic size I Standard tolerance grades

mm IT121 IT221 IT321 IT421 1 IT521 1 IT6 IT7 IT8 IT9 1 IT10 1 IT11 1 IT12 1 IT13 1 IT143)I IT153q ITI63) IT173)j ITl83)

up to Tolerances Above and in-

400 !a0 6302) 9 11 16 22 32 44 70 110 175 260 440 0,7 I,1 1.75 2,8 4,4 7 11

630 6002) 10 13 18 25 36 50 60 125 200 320 500 0,8 1.25 2 3.2 5 8 12,5

9 1,4 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 mm are given in annex A, table 5.

2) Values for standard tolerance grades IT1 to IT5 (incl.) for basic sizes over 506 mm 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

mm Upper deviation es

All standard tolerance grades ;;I IT71 IT8 1 up to

Above and in- -I- cluding - 3’)

at) bl) C cd d

- 270 -140 -60 -34 - 20

-321 I-161 I I I I

-10 0

-12 0

-14 0

-15 0

-17 0

60 100

=I= 100 120

120 140

250 I 280

260 1 315

-1 1 -210 -1251 I-621

!m 560 560 630 630 710

710 800

800 900

9cQ 1000 lOOil 1 120 I im 1 250

1250 1400

1400 16cCl

1600 1600 1600 2WO

2066 2 240

2240 2506

-290

I I I I -3m I I I I

I I I l-3= -1951 I-961 I ! ! !

1 -220 1 -110 1

-32 0

-1 -34 0

-38 0

I I I l-40 -240 -120

-260 -130

-290 -145

-460 I I I I

I I I 1 -520

1) 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 ITtl resulting deviations, i.e. f - , can be expressed in whole micrometres. 2



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IS0 266-l : 1966 (E)

fundamental deviations of shafts

Fundamental deviation values in micrometres

deviation values Lower deviation ei

T IT4 Up to IT3

I77 (incl.) and above IT7

All standard tolerance grades

P r S t U V X V Z za zb zc m

+2

+4

+6

+7

+8

+9

+11

+13

+15

+17

+20

+21

+23

+26

+30

+34

+40

+46

+66

+66

+76

n k

0 I 0 + 4

+ 8

+ 10

+ 12

+ 15

+ 6

+ 12

+ 16

+ 18

+I 0

+I 0

+I 0

+2 0

+2 0

+2 0

+3 0

+3 0

+4 0

-l-4 0

+4 0

+5 0

0 0

0 0

0 0

0 0

+ 17

+ 20

+ 23

+ 26

+ 32

+ 37

I 701+81l+971+ 1141+

1441+1721+2101+ 254 +

170 I +202 I +246 I+ 300 I+ 525

+ 63 + 27

+ 31

+34

+ 37

+ 40

+44

+ 50

+66

+643

+ 78

+ 62

+110

+135

1 + 66 I+ 106 1 + 146 1 + 210 1 +262 1 +310 1 + 3

+ 60 + 60 1 + 130 1 + 180 + 258 +310 +385 -I- 470 + 740 1 + !

+ 64 + 140 + 196 + 264 1 +340 1 +425 1 + 520 1 +

+106 + 190 t- 269 + 390 +475 S-590 + 730 + 900 + 62

+1150 +1 5m I+1900 +114 -I- 208 + 294 + 435 +530 +660 -I- 620 +lOQO I+l.100 . - 1 +I650 1 +2100 +I26 + _- 232 + 33 + 490 +595 +740 + 920

+6&l I I 1 1 +I 100 +I450 +I650 +2400 +I32 + 252 + 36-O + 640 +660 t620 +lOOO i-1250 +I600 +2100 +2600

+250 +120

+260 +300

+140 +330

~

+370 +I70

+400

4-440 +195

+460

+ 620 + 780 +I160

+ 660 + 640 +I300

+ 640 + 960 +1450

OI + 720 +I050 +1690 + 620 +1200 +1650

0 0

I 0 0

0 0

+ 920 +I350 +2000

+I000 +I500 +2300 -f-1100 +1650 +2500

+240 +550 l- +660

+I250 +1900 +29cxl +I400 +2100 +3200



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IS0 286-l : 1988 (E)

Table 3 - Numerical values of the

I I Fundamental deviation

Basic size Lower deviation EI

II IT6 IT7 IT6

J

All standard tolerance grades

F

t 6

+ 10

+ 13

+ 16

+20

+ 25

+ 62

+ 76

Above - =G - t4 - t6 - t8 -

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

EF - r-10 - t14

JS2) G H

+2 0 +4 0 t5 0

t6 0

+7 0

t9 0

+10 0

t12 0

+14 0

t15 0

t17 0

ii8 0

t20 0

+22 0

+24 0

t26 0

l-28 0

l-30 0

i-32 0

t34 0

t3a 0

f

+2 t5 - t5

t4 - +6 t8

t6 t10

+6 +10

t12

t15

+26

0 0 -2 -2 -1 +A - 4tA -4 -1 +A - 8+A - 6

3 6

10 14 16 24

~18 -

-,

-1 +A - 7tA - 7

2tA - 8tA - 8

-2+A -9+A -9

-2+A -11 +A -11

-3tA -13+A -13

+8

+10

t12 -- 40 t 310 +170 tm

50 + 320 +180 +130

65 + 340 +190 +I40

80 + 350 +200 t150

100 + 380 +220 +170

120 + 410 t240 +180

140 t 460 +260 t200

+14 t24

t28

30 40

+13 t18 60 86 60

+16 +22

+26

+34

-3+A 1 l-15+41 -15 1 t18

225 260 + 820 +420 +280 250 280 + 920 +4so +m

+190 i-110 280 315 t1050 +540 +330

315 I 355 1 +1m -l-600 +360 +210 +125

355 400 +135O +680 +403

01 1 -28 I

0 01 I-34 I

I I I

01 I-40 I -

-

-

0 -48

I I I 01 I-58 I

I I !

0 -88

01 I -76 I 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.



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IS0 286-l : 1988 (E)

fundamental deviations of holes

Fundamental deviation values in micrometres

values er deviation ES

Values for A UP

u/-z (incl.)

Standard tolerance grades above IT7 Standard tolerance grades

IT4

b yi i-i I

2

2 -

3 -

3 -

4 -

4

-

4

-

4 -

5 -

5 -

-

-

-

-

-

-

-

lulvlxlYl P R S T 2 ZA

- 6 - 10 - 14 - 18 - 20 - 26 - 32

- 12 - 15 - 19 - 23 - 28 - 35 - 42

- 15 - 19 - 23 - 28 -34 - 42 - 52

ZB I ZC IT: 0 1 i- - 1 -

1,E -

1,:

2 -

2 -

3

-

3

-

4 -

4 -

5 -

-

-

-

-

-

-

-

T7 0 T 6 -

7 -

8 -

9 -

11 -

13 -

15

-

17

-

m -

21 -

23 -

-

-

-

-

-

-

TI a s ? -

9 - 12 -

14 -

16 -

19 -

23

26

-

29 -

32 -

34 -

-

-

-

-

-

-

T5 IT6 0 0 13

2 3

3 3

3 4

4 5

5 6

5 7

6 7

6 9

7 9

7 11

7 13

i I

-4 -4

- 8+A 0

-lO+A 0

-12+A 0

-15+A

-17-!-A

-23+A

-27-!-A

-3l+A

-34+A

-37-14

-4O+A 0

-40 - 18 -23- 28 33

!3J- 64 - -

-39 -45 - 60- JJ

- 22 -29 35. 41 -47 -!3- 63- J3- 98 -

- 4l- 48 -55 -64 - J5- 88- 118

-- -- 46- 60 -68 -a- 94-112-149

-

- 26 -34 - 43 a I I I I -.~ 1 --

- 54 - JO -81 - 97 - 114 - 136 - 180

- 32

- 37

- 6201- 800 - JKII- 900 - J80-loo0

- 5ml- 670 - 6801-1150

- 9601-1250

-10% I-1 350

-68 -1261- 232]- 3301- 490 -595 -740 - 920 -1100 -1450

-132 - 252 - 360 - 540 -660 -820 -1000 -1250 -16M)

-44 - 78 -150-260-400-603

- -155 - 310 - 450 - 660

-68 -175 - 340 - 500 - 740 -185-380-560-940

-50 I

-56 -100 -210 - 430 - 620 - 940

-220 - 470 - 680 -1050

-250 - - -120

520 760 -1150

-260 - 580 - 840 -1m

I

-66 - $

I I ~~~ I - -I --- I I I I I

-140 -300 - 640 - 950 -1460

-33Ol- 72OI-1050~-l&M - 78

I ~~~ I -~- I --- --- -

- 170 -370 820 -1200 -1850

-4al I- 9201-1.250 -2@3J I --- I --- I --- -7m -195 -440 -1cm -1500 ____

-460 -1lco -1650 -2m

-240 -550 -1250 -1900 -2900

-580 -1400 -2100 -3200

- 92

-110

-136

3) (conch.) Examples: K7 in the range 18 to 30 mm: A = 8 pm, therefore ES = -2 f 8 = +6 pm

S6 in the range 18 to 30 mm: A = 4 pm, therefore ES = -35 + 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 mm.



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IS0 266-I : 1966 (EI

10 Bibliography

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 drawings - Linear and angular tolerances - Indications on drawings.

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

IS0 1829, Selection of tolerance zones for general purposes.

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

IS0 2692, Technical drawings - Geometrical tolerancing - Maximum material principle.

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

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.)



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is0 286-l : 1988 (E)

Annex A

Bases of the IS0 system of limits and fits (This annex forms an integral part of the standard.)

A.1 General

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.

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.

A.2 Basic 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.

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

Table 4 - Basic size steps

Values in millimetrc

a) Basic sizes up to 500 mm (incl.1

No subdivision

Values in millimetres

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

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



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IS0 286-l : 1988 (E)

geometrical mean (D) of the extreme sizes (Dt and L&l of that A.3.2 Derivation of standard tolerances (IT) for step, as follows : basic sizes up to and including 500 mm

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.3.2.1 Standard tolerance 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 approxi- mately scaled in geometrical progression between the values for IT1 and IT5.

A.3 Standard tolerance grades

A-3.1 General

The IS0 system of limits and fits provides for 20 standard tolerance grades designated ITOI, ITO, ITI, . . . , IT18 in the size range from 0 up to 500 mm (incl.), and 18 standard tolerance grades in the size range from 500 mm up to 3 150 mm (incl.1, designated IT1 to IT18.

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.

Table 5 - Numerical values for standard tolerances in grades IT01 and IT0

Basic size I

Standard tolerance grades

Above I Up to and including

IT01 I IT0

Tolerances urn

3 6

10 18 30 50 80

120 180 250 315 400

3 I 0,3 0,5 6 OS4 66

10 0,4 W3 18 0,5 023 30 ‘33 1 50 W-3 1 80 W3 12

120 1 I,5 180 12 2 250 2 3 315 2,5 4 400 3 5 500 4 6

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

including 500 mm

Values in micrometres

Standard tolerance grade

Formula for calculation where D is the geometric mean

of the basic size in millimetres

IT01 1) 0.3 + 0,008D

ITO’) 0,5 + 0,OlW

IT1 0,8 + 0,020D

I) 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, is calculated from the following formula :

i = 0,45 m + 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.).



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IS0 286-l : 1988 (El

Table 7 - Formulae for standard tolerances in grades IT1 to IT18

Basic size Standard tolerance grades

mm ITll) IT211 IT311 IT411 IT5 IT6 IT7 IT8 IT9 IT10 IT11 IT12 IT13 IT14 IT15 IT16 IT17 IT18

up to Above and in-

eluding Formulae for standard tolerances (Results in micrometres)

- 500 - - - - 7i 1Oi l6i 25i 40i 64 1OOi 160i 250i 4COi 640i 1OOOi 16ooi 25GOi 5Qo 3150 21 2.71 3,71 51 71 101 16r 251 4OI 641 1001 1602 2501 4001 6401 10001 16001 25031

1 I See A.3.2.1.

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

Table 8 - Rounding for IT values up to and including standard tolerance grade IT11

Roundinn values in micrometres

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, is calculated from the following formula :

Calculated values obtained from the formulae

given in A.3.2 and A.3.3

I = 0,004D + 2,l Above Up to and

including

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

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.

0 60 60 100

100 200 200 500 500 1000

1000 2000 2000 5000 5Oao 10 000

1ocoo 20000 20 000 5oooo

Basic size

+!I% / 3%JL

Rounding in multiples of

1 1 1 2 5 5

10 10 - 20 - 50 - 100 - 200 - 500 - 1000

Example :

IT20 = IT15 x IO = 6491 x 10 = 64001 NOTES

NOTES

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

A.3.4 Rounding of values for standard tolerances

A.4 Derivation of fundamental 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 Fundamental deviations for shafts

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

The calculated values of standard tolerances in grades above The fundamental deviation given by the formulae in table 9 is, IT1 1 do not require rounding off because they are derived from in principle, that corresponding to the limits closest to the zero values of tolerance grades IT7 to IT1 1, which have already been line, i.e. the upper deviation for shafts a to h and the lower rounded off. deviation for shafts k to zc.



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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 inde- pendent of the selected grade of tolerance (even if the formula includes a term involving ITnL

A.4.2 Fundamental deviations 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 deviations except for the following :

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 :

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

A = IT7 - IT6 = 21 - 13 = 8 pm

Hole-basis fit Shaft-basis fit

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

Figure 20 - Diagrammatic representation of the rule given in A.4.2bl

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 inde- pendent of the selected grade of tolerance (even if the formula includes a term involving ITn).

A.4.3 Rounding of values for fundamental deviations

NOTE - The rule given in b) above is only applicable for basic sizes over 3 mm 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.

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 :I988 (El

r

Table 9 - Formulae for fundamental deviations for shafts and holes

Basic size mm

up to Above and in-

cluding

Shafts Formulael) Holes Basic size mm

- where D is the Funda- Sign

(negative geometric mean Sign

mental Desig- of the basic size Desig- (negative Funda-

deviation pos~~ve~ nation in millimetres nation pos%e)

mental Above up to

and in- deviation ciuding

1 120 120 500

1 160 160 500

0 40 40 500

a 265 + I,30 - es EI + A 1 120

3,5D 120 500

b es = 140 + 0,850 - EZ + B 1 160

= 1,8D 160 500 5200.2 EI C 0

C - es + 40 95 + 0,8D 40 500

IO

3 150 3150

cd

d e

-

- -

es

es es

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

1600.44 1 ID0141

EI + CD 0 10

EI + D 0 3 150 EI + E 0 3 150

lo ( ef / - 1 o I lo I

0

0 500

3 150 is + es 0,5 ITn Ei + JS 0 3 150 - ei -

5003) k

+ - ei

033 G ES K4) 0 5005)

3 150 No sinn Deviation = 0 No sian 500 3 150

0 5cMl 50034 n + ei ES N4) 0 500 - 500 3150 0,040 + 21 500 3 150

0 5ca IT7 + 0 to 5 0 500 500 3 150

P + ei ES - P4) 0,07W + 37,8 500 3 150 Geometric mean

0 3 150 r + ei of the values for ES - Fz4) 0 3150 P, p and S, s

0 50 0 50 S + ei

IT8 + 1 to 4 ES - s4) 50 3 150 IT7 + 0,4D 50 3150 24 3 156 t + ei IT7 + 0,630 ES - T4) 24 3150

0 1 3150 1 U + ei 1 IT7 + D ES - 1 u4) 1 0 1 3150 14 I 500 I V I + I ei 1 IT7 + 1,250 1 ES 1 - 1 V4) 1 14 I 500 0 1 500 1 X t ei 1 IT7 + 1,6D 1 ES 1 - 1 X4) 1 0 1 500

18 I 500 I V I + I ei 1 IT7 + W 1 ES I - I Y4) I 18 I 500

0 1 500 1 Z + ei 1 IT7 + 2,5D 1 ES 1 - 1 24) 0 1 500 0 I 500 I za I + I ei 1 IT8 + 3.150 t ES 1 - 1 ZA4) 1 0 I 5oa 0 500 zb + ei IT9 + 40 ES - ZB 41 0 5-00 0 5cil ZC + ei IT10 + 50 ES - zc 41 0 500

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

Calculated values obtained from the formulae given in table 9

w

Above

5 45 50

loo 200 300 5ocl 550 500 800

1000 2oOa

. * .

20 x IOn 50 x 10”

loo x 10”

Up to and including

45 50

100 200 300 500 550 500 800

1000 2ooo 5Gvo

* . *

50 x 10n loo x IOn 200 x 10n

-I-

Basic size

Rounding values in micrometres

up to 590 mm Encl.1 above 509 mm up to 3 150 mm Encl.1

Fundamental deviations

a to g A to G

k to zc d to u KtoZC D to U

Rounding in multiules of

1 2 5 5

10 10 10 20 20 20 50

1 1 1 2 2 5 5 5

IO 20 50

100

1 1 2 5

10 10 20 20 20 20 50

100

. . .

1 x 10” 2 x 10” 5 x 10”



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IS0 286-l : 1888 (E)

Annex B

Examples of the use of IS0 286-l (This annex forms an integral part of the standard.)

B.l General

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

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.

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.

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 prac- tically 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.

6.3 Examples

B.3.1 Determining the limits of size for a shaft 0 4Ogll

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

Standard tolerance = 160 pm (from table 1)

Fundamental deviation = -9 pm (from table 2)

Upper deviation = fundamental deviation = -9 pm

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

Limits of size :

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 C

Equivalent 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, etc. in which the term is defined (or the most 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. Square brackets indicate that the word(s) placed between them may replace all or some of the preceding words.

Short explanations as regards the term have been presented in note form.

C.3 Recommendations for the user

It is recommended that the users, for convenience, re-arrange the vocabulary alphabetically in their own languages and number them accordingly on the left-hand side of the table,



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IS0 286-l : 1988 (EI



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ISO 286-l : 1999 (El



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IS0 266-I : 1666 (E)



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IS0 266-I : 1666 (E)

I I I



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1s0 266-l :I988 E)

I I :

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IS0 286-l : 1988 (El



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IS0 266-l : 1666 (E)

UDC 621.763.1/.2

Descriptors : dimensional tolerances, fits, fundamental tolerances, definitions, symbols, designation, schematic representation, dimensions.

Price based on 30 pages



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Documents

ISO Tolerance Part 1