SIST
SIST ISO 286-1:1999
(Main)ISO system of limits and fits -- Part 1: Bases of tolerances, deviations and fits
ISO system of limits and fits -- Part 1: Bases of tolerances, deviations and fits
This part gives the bases of the ISO system of limits and fits together with the calculated values of the standard tolerances and fundamental deviations. It also gives terms and definitions together with associated symbols.
Système ISO de tolérances et d'ajustements -- Partie 1: Base des tolérances, écarts et ajustements
La présente partie de l'ISO 286 fixe les bases d'un système ISO de tolérances et d'ajustements et donne les valeurs calculées des tolérances fondamentales et des écarts fondamentaux correspondants. Les valeurs font foi pour l'application du système (voir aussi chapitre A.1). La présente partie de l'ISO 286 donne la terminologie et les définitions à utiliser ainsi que les symboles correspondants.
Le système ISO de tolérances et d'ajustements fournit un système de tolérances et d'écarts applicables aux pièces lisses. Pour plus de simplicité et étant donné l'importance particulière des pièces cylindriques à section circulaire, seules celles-ci sont prévues explicitement. Mais il reste bien entendu que les tolérances et écarts donnés dans la présente Norme internationale s'appliquent également aux pièces lisses de section autre que circulaire. En particulier, les termes généraux «alésage» ou «arbre» désignent également l'espace, contenant ou contenu, compris entre deux faces (ou plans tangents) parallèles d'une pièce quelconque, tel que largeur de rainure, épaisseur de clavette, etc. Le système s'explique également à l'ajustement d'éléments cylindriques ou à l'ajustement de pièces présentant des éléments à faces parallèles, du type clavette et rainure de clavette, etc. NOTE -- Le système ne prévoit aucune règle d'ajustement pour des pi 216èces constituées d'éléments de forme géométrique autre que simple. Dans la présente partie de l'ISO 286, «forme géométrique simple» signifie une surface cylindrique ou deux plans parallèles.
Sistem mejnih mer in ujemov ISO - 1. del: Osnove toleranc, odstopkov in ujemov
General Information
Status
Withdrawn
Publication Date
31-Oct-1995
Withdrawal Date
11-May-2010
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
11-May-2010
Due Date
03-Jun-2010
Completion Date
12-May-2010
RELATIONS
Standards Content (sample)
IS0
INTERNATIONAL STANDARD
286-l
First edition
1988-09-15
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION
ORGANISATION INTERNATIONALE DE NORMALISATION
MEXJJYHAPOAHAR OPTAHM3A~Mfl f-t0 CTAHflAPTM3A~MM
IS0 system of limits and fits -
Part I :
Bases of tolerances, deviations and fits
Syst&me IS0 de tokkances et d’ajustements -
Partie 7 : Base des tokances, harts et ajustements
Reference number
IS0 286-l : 1988 (E)
---------------------- Page: 1 ----------------------
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 memberbody interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, govern-
mental 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 286 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 286 are as follows:
a) 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 calculatedvalues 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 js 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 500 to 3 150 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.
aligned required
The principles, terminology and symbols
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, 1988
Printed in Switzerland
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ISO286-1:1988 EI
Contents
Introduction. .......................................................
Scope .............................................................
Field of application ..................................................
References .........................................................
Terms and definitions ................................................
Symbols, designation and interpretation of tolerances, deviations
andfits.. ..........................................................
6 Graphical representation .............................................
7 Reference temperature ...............................................
8 Standard tolerances for basic sizes up to 3 150 mm. ...................... 10
Fundamental deviations for basic sizes up to 3 150 mm ...................
Bibliography ........................................................ 16
Annexes
............................... 17
A Bases of the IS0 system of limits and fits
....................................... 23
B Examples of the use of IS0 286-l
C Equivalentterms ....................................................
. . .
III
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INTERNATIONAL STANDARD IS02864 : 1988 (E)
IS0 system of limits and fits -
Part 1:
Bases of tolerances, deviations and fits
0 Introduction 2 Field of application
The need for limits and fits for machined workpieces was The IS0 system of limits and fits provides a system of
brought about mainly by the inherent inaccuracy of manufac- tolerances and deviations suitable for plain workpieces.’
turing methods, coupled with the fact that “exactness” of sizewas found to be unnecessary for most workpieces. In order For simplicity and also because of the importance of cylindrical
that function could be satisfied, it was found sufficient to workpieces of circular section, only these are referred to ex-
manufacture a given workpiece so that its size lay within two plicitly. It should be clearly understood, however, that the
tolerances and deviations given in this International Standardpermissible limits, i.e. a tolerance, this being the variation in
size acceptable in manufacture. equally apply to workpieces of other than circular section.
In particular, the general term “hole” or “shaft” can be takenSimilarly, where a specific fit condition is required between
mating workpieces, it is necessary to ascribe an allowance, as referring to the space contained by (or containing) the two
parallel faces (or tangent planes) of any workpiece, such as theeither positive or negative, to the basic size to achieve the re-
quired clearance or interference, i.e. a “deviation”. width of a slot or the thickness of a -key.
With developments in industry and international trade, it The system also provides for fits between mating cylindrical
became necessary to develop formal systems of limits and fits, features or fits between workpieces having features with
parallel faces, such as the fit between a key and keyway, etc.firstly at the industrial level, then at the national level and later
at the international level.
NOTE - It should be noted that the system is not intended to provide
fits for workpieces with features having other than simple geometric
This International Standard therefore gives the internationally
forms.
accepted system of limits and fits.
For the purposes of this part of IS0 286, a simple geometric form
consists of a cylindrical surface area or two parallel planes.
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.
3 References
Annex C gives a list of equivalent terms used in IS0 286 and
NOTE - See also clause 10.
other International Standards on tolerances.
IS0 1, Standard reference temperature for industrial length
measurements.
1 Scope
IS0 286-2, IS0 system of limits and fits - Part 2: Tables of
standard tolerance grades and limit deviations for holes and
This part of IS0 286 gives the bases of the IS0 system of limits
shafts.
and fits together with the calculated values of the standard
tolerances and fundamental deviations. These values shall be
IS01 R 1938, IS0 system of limits and fits - Inspection of plain
taken as authoritative for the application of the system (see also
workpieces. 1 )
clause A. 1).
This part of IS0 286 also gives terms and definitions together IS0 8015, Technical drawings - Fundamental tolerancing
with associated symbols. principle.1) At present under revision.
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Is0 286-1 : 1988 E)
4.5 zero line: In a graphical representation of limits and fits,
4 Terms and definitions
the straight line, representing the basic size, to which the devi-
For the purposes of this International Standard, the following ations and tolerances are referred (see figure 7).
terms and definitions apply. It should be noted, however, thatn, the zero line is
According to conventio drawn horizontally,
some of the terms are defined in a more restricted sense than in
with positive deviations shown above and negative deviations
common usage.
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).
Zero line (4.5)
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
Figure 1 - Basic size, and maxim urn and minimum
numerical value of a linear dimension.
limits of size
4.3.1 basic size; nominal size: The size from which the
4.6 deviation: The algebraic difference between a size
limits of size are derived by the application of the upper and
(actual size, limit of size, etc.) and the corresponding basic size.
lower deviations (see figure 1).
NOTE - Symbols for shaft deviations are lower case letters (es, ei) and
NOTE - The basic size or a number, symbols for hole deviations are upper case letters (Es, EI) (see
can be ae.g. 32; 15; 8,75; 0,5; etc. figure 2).
limit deviations : Upper deviation and lower deviation.
4.6.1
4.3.2 actual size: The size of a feature, obtained by
measurement.
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).
4.3.2.1 actual local size: Any individual distance at any
cross-section of a feature, i.e. any size measured between any
4.6.1.2 lower deviation (EL ei) : The algebraic difference
two opposite points.
between the minimum limit of size and the corresponding basic
size (see figure 2).
4.3.3 limits of size: The two extreme permissible sizes of a
feature, between which the actual size should lie, the limits of 4.6.2 fundamental deviation: For the purposes of the IS0
size being included. system of limits and fits, that deviation which defines theposition of the tolerance zone in relation to the zero line (see
figure 2).
4.3.3.1 maximum limit of size: The greatest permissible
size of a feature (see figure 1). NOTE - This may be either the upper or lower deviation, but, accord-
ing to convention, the fundamental deviation is the one nearest thezero line.
4.3.3.2 minimum limit of size : The smallest permissible size
of a feature (see figure 1).
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.
4.4 limit system: A system of standardized tolerances and
deviations.
NOTE - The tolerance is an absolute value without sign.
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IS0 286-l I 1988 E)
- Lower deviation (EI, ei 1 (4.6.1.2)
Clearance (4.8)
Tolerance zone (4.7.3)
tolerance (4.7)
- (ES, es)
P Zero line (4.5) (4.6.1.1) ,~
l - I w
2 F-
Figure 3 - Clearance
Figure 2 - Conventional representation of a
tolerance zone
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).
4.7.1 standard tolerance (IT) : For the purposes of the IS0
system of limits and fits, any tolerance belonging to this
4.8.2 maximum clearance: In a clearance or transition fit,
system.
the positive difference between the maximum limit of size of
the hole and the minimum limit of size of the shaft (see
NOTE - The letters of the symbol IT stand for “International
figures 4 and 5).
Tolerance” grade.
4.9 interference : The negative difference between the sizes
4.7.2 standard tolerance grades: For the purposes of the
of the hole and the shaft, before assembly, when the diameter
IS0 system of limits and fits, a group of tolerances (e.g. IJ7),
of the shaft is larger than the diameter of the hole (see
considered as corresponding to the same level of accuracy for
figure 6).
all basic sizes.
4.9.1 minimum interference: In an interference fit, the
4.7.3 tolerance zone : In a graphical representation of
negative difference, before assembly, between the maximum
tolerances, the zone, contained between two lines representing
limit of size of the hole and the minimum limit of size of the
the maximum and minimum limits of size, defined by the
shaft (see figure 7).
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, I): 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.
The standard tolerance factor I is applied to basic sizes greater than
500 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 286-1 : 1988 (E)
Maximum
Minimum
Maximum
clearance
interference ‘-1 I- interference
(4.8.2)
Maximum
Interference fit
Figure 7 -
interference 2
(4.9.2)
4.10.1 clearance fit: A fit that always provides a clearance
Figure 5 - Transition fit
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
Hole
Shaft
Shaft
Figure 8 - 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 ex-
treme case, equal to the minimum size of the shaft (see
figure 9).
Figure 6 - Interference
Shaft
4.9.2 maximum interference: In an interference or tran-
Shaft
sition 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,
Zero line .
before assembly, between the sizes of the two features (the t
Hole Hole
hole and the shaft) which are to be assembled.
NOTE - The two mating parts of a fit have a common basic size. Schematic representation of interference fits
Figure 9 ----------------------- Page: 8 ----------------------
IS0 286-l : 1988 (El
4.11.2 hole-basis. system of fits : A system of fits in which
4.103 transition fit: A fit which may provide either a
the required clearances or interferences are. obtained by
clearance or an interference between the hole and shaft when
associating shafts of various tolerance classes with holes of a
assembled, depending on the actual sizes of the hole and shaft,
single tolerance class.
i.e. the tolerance zones of the hole and the shaft overlap com-
pletely or in part (see figure IO).
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
Shaft
. . .
to the basic size, i.e. the lower deviation is zero (see figure 12).
Hole
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.
- Basic size (4.3.1)
4.11.1 shaft-basis system of fits: A system of fits in which
the required clearances or interferences are obtained by
NOTES
associating holes of various tolerance classes with shafts of a
single tolerance class.
1 The horizontal continuous lines represent the fundamental devi-
ations for holes or shafts.
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
2 The dashed lines represent the other limits and show the possibility
identical to the basic size, i.e. the upper deviation is zero (see
of different combinations between holes and shafts, related to their
figure I I).
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),
Shaft “h”
the minimum (lower) limit of size for an internal feature
(hole).
NOTE - Previously called “GO limit”.
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
NOTES material size for the feature, i.e.
1 The horizontal continuous lines represent the fundamental devi-
the minimum (lower) limit of size for an external feature
ations for holes or shafts.
(shaft),
2 The dashed lines represent the other limits and show the possibility
of different combinations between holes and shafts, related to their -
the maximum (upper) limit of size for an internal feature
grade of tolerance (e.g. G71h4, H6/h4, M5/h4).
(hole).
- Previously called “NOT GO limit”.
Figure 11 - Shaft-basis system of fits NOTE
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IS0 286-1 : 1988 (E)
Examples :
5 Symbols, designation and interpretation
of tolerances, deviations and fits
32H7
8OjsI5
10096
5.1 Symbols
-0 012
IO0 -0:034
5.1 .l Standard tolerance grades
ATTENTION - In order to distinguish between holes and
The standard tolerance grades are designated by the letters IT
shafts when transmitting information on equipment with
followed by a number, e.g. IJ7. When the tolerance grade is
limited character sets, such as telex, the designation shall be
associated with (a) letter(s) representing a fundamental
prefixed by the following letters:
deviation to form a tolerance class, the letters IT are omitted,
e.g. h7. -
H or h for holes;
- S or s for shafts.
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 Examples :
general use, are given in annex A for information purposes.
5OH5 becomes H5OH5 or h5Oh5
5Oh6 becomes S5OH6 or s5Oh6
5.1.2 Deviations
This method of designation shall not be on
drawings.
5.1.2.1 Position of tolerance zone
The position of the tolerance zone with respect to the zero line,
5.2.3 Fit
which is a function of the basic size, is designated by (an) upper
case letter(s) for holes (A . . . ZC) or (a) lower case letter(s) for
A fit requirement between mating features shall be designated
shafts (a . . . zc) (see figures I3 and 14).
NOTE - To avoid confusion, the following letters are not used :
a) the common basic size;
I, i; L, I; 0, 0; Q, q; W, w.
b) the tolerance class symbol for the hole;
c) the tolerance class symbol for the shaft.
5.1.2.2 Upper deviations
Examples :
The upper deviations are designated by the letters “ES” for
Ii7
52H7lg6 or 52 -
holes and the letters “es” for shafts.
ATTENTION - In order to distinguish between the hole and
5.1.2.3 Lower deviations
the shaft when transmitting information on equipment with
limited character sets, such as telex, the designation shall be
The lower deviations are designated by the letters “El” for
prefixed by the following letters:
holes and the letters “ei” for shafts.
- H or h for holes;
5.2 Designation
- S or s for shafts;
and the basic size repeated.
5.2.1 Tolerance class
Examples :
A tolerance class shall be designated by the letter(s) represent-
ing the fundamental deviation followed by the number
52H7/g6 becomes H52H7/S52G6 or h52h7/s52g6
representing the standard tolerance grade.
This method of designation shall not be used on
Examples :
drawings.
H7 (holes)
h7 (shafts)
5.3 Interpretation of a toleranced size
5.3.1 Tolerance indication in accordance with IS0 8015
5.2.2 Toleranced size
The tolerances for workpieces manufactured to drawings
A toleranced size shall be designated by the basic size followed
marked with the notation, Tolerancing IS0 8015, shall be
by the designation of the required tolerance class, or the ex-
plicit deviations. interpreted as indicated in 5.3. I. I and 5.3.1.2.
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Is0 286-I : 1988 (El
a) Holes (internal features)
b) Shafts (external features)
NOTES
I 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---------------------- Page: 11 ----------------------
60286-1:1988 E)
I-- l-
. .
. .
CL) LLJ
0 0
z z
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IS0 286-k 1988 a(E)
6 Graphical representation
53.1 .I Linear size tolerances
The major terms and definitions given in clause 4 are illustrated
A linear size tolerance controls only the actual local sizes (two-
in figure 15.
point measurements) of a feature, but not its form deviations
(for example circularity and straightness deviations of a cylin-
In practice, a schematic diagram such as that shown in
drical feature or flatness deviations of parallel surfaces). There
figure 16 is used for simplicity. In this diagram, the axis of the
is no control of the geometrical interrelationship of individual
workpiece, which is not shown in the figure, according to con-
features by the size tolerances. (For further information, see
vention always lies below the diagram.
ISO/R 1938 and IS0 8015.)
two deviations of the hole are
In the example illustrated, the
5.3.1.2 Envelope requirement
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 ad-
Upper deviation (4.6.1.1) -
dition to the dimension and tolerance. This indicates a mutual
Lower deviation (4.6.1.2)
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 1938 and Hole (4.2)
r r
IS0 8015.)
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.
53.2 Tolerance indication not in accordance with
IS0 6015
The tolerances for workpieces manufactured to drawings
which do not have the notation, Tolerancing IS0 6015, 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 con-
tacts 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
Minimum limit of size (4.3.3.2) -
least material limit of size.
Maximum limit of size (4.3.3.1)
b) For shafts
Basic size (4.3.1)
The diameter of the smallest perfect imaginary cylinder,
which can be circumscribed about the shaft so that it just
Figure 15 - Graphical representation
contacts the highest points of the surface, should not be
larger than the maximum material limit of size. The mini-
mum diameter at any position on the shaft shall be not less
than the least material limit of size.
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.
Unless otherwise specified, and subject to the above require-
ments, departures from a perfect cylinder may reach the full 2
value of the diameter tolerance specified. For further informa-
Shaft
tion, see ISO/R 1938.
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
Figure 16 - Simplified schematic diagram
circularity and/or straightness (see IS0 1101).
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IS0 286-l : 1988 (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 OC (see IS0 I). The fundamental deviations for holes and their respective sign
( + or - ) are shown in figure 18. Values for the fundamentaldeviations are given in table 3.
The upper deviation (ES) and lower deviation (H) are
8 Standard tolerances for basic sizes up to
established from the fundamental deviation and the standard
315Omm
tolerance grade (IT) as shown in figure 18.
8.1 Basis of the system
Deviations A to H Deviations K to ZC
The bases for calculating the standard tolerances are given in
(not valid for tolerance grades
annex A.
less than or equal to IT8
of deviation K and tolerance
class M8)
8.2 Values of standard tolerance grades (IT)
Values of standard tolerance grades IT1 to IT18 inclusive are
Zero line
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.
ES = negative ( - 1 funda-
EI = positive (+ 1 funda-
9 Fundamental deviations for basic sizes up
mental deviation mental deviation
to315Omm
ES = EI + IT EI = ES - IT
9.1 Fundamental deviations for shafts
[except deviation js (see 9.3)]
Figure 18 - Deviations for holes
The fundamental deviations for shafts and their respective sign
( + or - 1 are shown in figure 17. Values for the fundamental
9.3 Fundamental deviations js and JS
deviations are given in table 2.
(see figure 19)
The upper deviation (es) and lower deviation (ei) are estab-
The information given in 9.1 and 9.2 does not apply to fun-
lished from the fundamental deviation and the standard
damental deviations js and JS, which are a symmetrical
tolerance grade (IT) as shown in figure 17.
distribution of the standard tolerance grade about the zero line,
i.e. for js:
Deviations a to h Deviations k to zc IT
es = ei = -
and for JS:
ES = EI.= -
Zero line
es ES
ei = positive ( + ) funda-
es = negative ( - 1 funda-
Shaft
I Hole
mental deviation
mental deviation
ei = es - IT es = ei + IT
Figure 17 - Deviations for shafts
Deviations js and JS
Figure 19 -
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IS0 286-1 : 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).
Numerical values of standard tolerance grades IT for basic sizes up to 3 150 mm ‘)
Table 1 -Standard tolerance grades
Basic size
IT7 IT8 1 IT8 1 IT10 ] IT11 1 IT12 1 IT13 1 lTl43)1
IT153) 1 IT1631 ITl73)I IT1831
up to
Tolerances
Above and in-
cluding mm
IJm
- 33) 0,8 I,2 2 3 4 6 10 14 25 40
60 0,l 0,14 0,25 0,4 0,6 1 114
3 6 1
1,5 2,5 4 5 8 12 18 30 48 75 0,12 0,18 0,3 0,48 0,75 1,2
I,8
6 10 1 I,5 2,5 4
6 9 15 22 36 58 90 0,15 0,22 0,36 0,58 0;9 I,5
2,2
10 18 I,2 2 3 5 8 11 18 27 43
70 110 0,18 0,27 0,43 0,7 1,1' I,8 2,7
18 30
I,5 2,5 4 6 9 13 21 33 52 84 130 0,21
0,33 0,52 0,84 I,3 2,l 3,3
30 50 I,5 2,5 4 7 11 16 25
39 62 100 160 0,25 0,39 0,62 1 1,6 2,5 3,9
50 80 2,, 3 5 8 13 19 30 46 74
120 190 0,3 0,46 0,74 1,2 I,9 3 4,6
80 120
2,5 4 6 10 15 22 35 54 87 140 220 0,35
0,54 0,87 I,4 2,2 3,5 5,4-
120 180 3,5 5 8 12 18 25
40 63 100 160 250 0,4 0,63 1 I,6 2,5 4 613
180 250 4,5 7 10 14
...
SLOVENSKI STANDARD
SIST ISO 286-1:1999
01-marec-1999
Sistem mejnih mer in ujemov ISO - 1. del: Osnove toleranc, odstopkov in ujemov
ISO system of limits and fits -- Part 1: Bases of tolerances, deviations and fits
Système ISO de tolérances et d'ajustements -- Partie 1: Base des tolérances, écarts et
ajustementsTa slovenski standard je istoveten z: ISO 286-1:1988
ICS:
17.040.10 Tolerance in ujemi Limits and fits
SIST ISO 286-1:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------SIST ISO 286-1:1999
---------------------- Page: 2 ----------------------
SIST ISO 286-1:1999
IS0
INTERNATIONAL STANDARD
286-l
First edition
1988-09-15
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION
ORGANISATION INTERNATIONALE DE NORMALISATION
MEXJJYHAPOAHAR OPTAHM3A~Mfl f-t0 CTAHflAPTM3A~MM
IS0 system of limits and fits -
Part I :
Bases of tolerances, deviations and fits
Syst&me IS0 de tokkances et d’ajustements -
Partie 7 : Base des tokances, harts et ajustements
Reference number
IS0 286-l : 1988 (E)
---------------------- Page: 3 ----------------------
SIST ISO 286-1:1999
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 memberbody interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, govern-
mental 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 286 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 286 are as follows:
a) 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 calculatedvalues 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 js 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 500 to 3 150 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.
aligned required
The principles, terminology and symbols
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, 1988
Printed in Switzerland
---------------------- Page: 4 ----------------------
SIST ISO 286-1:1999
ISO286-1:1988 EI
Contents
Introduction. .......................................................
Scope .............................................................
Field of application ..................................................
References .........................................................
Terms and definitions ................................................
Symbols, designation and interpretation of tolerances, deviations
andfits.. ..........................................................
6 Graphical representation .............................................
7 Reference temperature ...............................................
8 Standard tolerances for basic sizes up to 3 150 mm. ...................... 10
Fundamental deviations for basic sizes up to 3 150 mm ...................
Bibliography ........................................................ 16
Annexes
............................... 17
A Bases of the IS0 system of limits and fits
....................................... 23
B Examples of the use of IS0 286-l
C Equivalentterms ....................................................
. . .
III
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SIST ISO 286-1:1999
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SIST ISO 286-1:1999
INTERNATIONAL STANDARD IS02864 : 1988 (E)
IS0 system of limits and fits -
Part 1:
Bases of tolerances, deviations and fits
0 Introduction 2 Field of application
The need for limits and fits for machined workpieces was The IS0 system of limits and fits provides a system of
brought about mainly by the inherent inaccuracy of manufac- tolerances and deviations suitable for plain workpieces.’
turing methods, coupled with the fact that “exactness” of sizewas found to be unnecessary for most workpieces. In order For simplicity and also because of the importance of cylindrical
that function could be satisfied, it was found sufficient to workpieces of circular section, only these are referred to ex-
manufacture a given workpiece so that its size lay within two plicitly. It should be clearly understood, however, that the
tolerances and deviations given in this International Standardpermissible limits, i.e. a tolerance, this being the variation in
size acceptable in manufacture. equally apply to workpieces of other than circular section.
In particular, the general term “hole” or “shaft” can be takenSimilarly, where a specific fit condition is required between
mating workpieces, it is necessary to ascribe an allowance, as referring to the space contained by (or containing) the two
parallel faces (or tangent planes) of any workpiece, such as theeither positive or negative, to the basic size to achieve the re-
quired clearance or interference, i.e. a “deviation”. width of a slot or the thickness of a -key.
With developments in industry and international trade, it The system also provides for fits between mating cylindrical
became necessary to develop formal systems of limits and fits, features or fits between workpieces having features with
parallel faces, such as the fit between a key and keyway, etc.firstly at the industrial level, then at the national level and later
at the international level.
NOTE - It should be noted that the system is not intended to provide
fits for workpieces with features having other than simple geometric
This International Standard therefore gives the internationally
forms.
accepted system of limits and fits.
For the purposes of this part of IS0 286, a simple geometric form
consists of a cylindrical surface area or two parallel planes.
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.
3 References
Annex C gives a list of equivalent terms used in IS0 286 and
NOTE - See also clause 10.
other International Standards on tolerances.
IS0 1, Standard reference temperature for industrial length
measurements.
1 Scope
IS0 286-2, IS0 system of limits and fits - Part 2: Tables of
standard tolerance grades and limit deviations for holes and
This part of IS0 286 gives the bases of the IS0 system of limits
shafts.
and fits together with the calculated values of the standard
tolerances and fundamental deviations. These values shall be
IS01 R 1938, IS0 system of limits and fits - Inspection of plain
taken as authoritative for the application of the system (see also
workpieces. 1 )
clause A. 1).
This part of IS0 286 also gives terms and definitions together IS0 8015, Technical drawings - Fundamental tolerancing
with associated symbols. principle.1) At present under revision.
---------------------- Page: 7 ----------------------
SIST ISO 286-1:1999
Is0 286-1 : 1988 E)
4.5 zero line: In a graphical representation of limits and fits,
4 Terms and definitions
the straight line, representing the basic size, to which the devi-
For the purposes of this International Standard, the following ations and tolerances are referred (see figure 7).
terms and definitions apply. It should be noted, however, thatn, the zero line is
According to conventio drawn horizontally,
some of the terms are defined in a more restricted sense than in
with positive deviations shown above and negative deviations
common usage.
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).
Zero line (4.5)
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
Figure 1 - Basic size, and maxim urn and minimum
numerical value of a linear dimension.
limits of size
4.3.1 basic size; nominal size: The size from which the
4.6 deviation: The algebraic difference between a size
limits of size are derived by the application of the upper and
(actual size, limit of size, etc.) and the corresponding basic size.
lower deviations (see figure 1).
NOTE - Symbols for shaft deviations are lower case letters (es, ei) and
NOTE - The basic size or a number, symbols for hole deviations are upper case letters (Es, EI) (see
can be ae.g. 32; 15; 8,75; 0,5; etc. figure 2).
limit deviations : Upper deviation and lower deviation.
4.6.1
4.3.2 actual size: The size of a feature, obtained by
measurement.
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).
4.3.2.1 actual local size: Any individual distance at any
cross-section of a feature, i.e. any size measured between any
4.6.1.2 lower deviation (EL ei) : The algebraic difference
two opposite points.
between the minimum limit of size and the corresponding basic
size (see figure 2).
4.3.3 limits of size: The two extreme permissible sizes of a
feature, between which the actual size should lie, the limits of 4.6.2 fundamental deviation: For the purposes of the IS0
size being included. system of limits and fits, that deviation which defines theposition of the tolerance zone in relation to the zero line (see
figure 2).
4.3.3.1 maximum limit of size: The greatest permissible
size of a feature (see figure 1). NOTE - This may be either the upper or lower deviation, but, accord-
ing to convention, the fundamental deviation is the one nearest thezero line.
4.3.3.2 minimum limit of size : The smallest permissible size
of a feature (see figure 1).
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.
4.4 limit system: A system of standardized tolerances and
deviations.
NOTE - The tolerance is an absolute value without sign.
---------------------- Page: 8 ----------------------
SIST ISO 286-1:1999
IS0 286-l I 1988 E)
- Lower deviation (EI, ei 1 (4.6.1.2)
Clearance (4.8)
Tolerance zone (4.7.3)
tolerance (4.7)
- (ES, es)
P Zero line (4.5) (4.6.1.1) ,~
l - I w
2 F-
Figure 3 - Clearance
Figure 2 - Conventional representation of a
tolerance zone
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).
4.7.1 standard tolerance (IT) : For the purposes of the IS0
system of limits and fits, any tolerance belonging to this
4.8.2 maximum clearance: In a clearance or transition fit,
system.
the positive difference between the maximum limit of size of
the hole and the minimum limit of size of the shaft (see
NOTE - The letters of the symbol IT stand for “International
figures 4 and 5).
Tolerance” grade.
4.9 interference : The negative difference between the sizes
4.7.2 standard tolerance grades: For the purposes of the
of the hole and the shaft, before assembly, when the diameter
IS0 system of limits and fits, a group of tolerances (e.g. IJ7),
of the shaft is larger than the diameter of the hole (see
considered as corresponding to the same level of accuracy for
figure 6).
all basic sizes.
4.9.1 minimum interference: In an interference fit, the
4.7.3 tolerance zone : In a graphical representation of
negative difference, before assembly, between the maximum
tolerances, the zone, contained between two lines representing
limit of size of the hole and the minimum limit of size of the
the maximum and minimum limits of size, defined by the
shaft (see figure 7).
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, I): 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.
The standard tolerance factor I is applied to basic sizes greater than
500 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
---------------------- Page: 9 ----------------------
SIST ISO 286-1:1999
IS0 286-1 : 1988 (E)
Maximum
Minimum
Maximum
clearance
interference ‘-1 I- interference
(4.8.2)
Maximum
Interference fit
Figure 7 -
interference 2
(4.9.2)
4.10.1 clearance fit: A fit that always provides a clearance
Figure 5 - Transition fit
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
Hole
Shaft
Shaft
Figure 8 - 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 ex-
treme case, equal to the minimum size of the shaft (see
figure 9).
Figure 6 - Interference
Shaft
4.9.2 maximum interference: In an interference or tran-
Shaft
sition 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,
Zero line .
before assembly, between the sizes of the two features (the t
Hole Hole
hole and the shaft) which are to be assembled.
NOTE - The two mating parts of a fit have a common basic size. Schematic representation of interference fits
Figure 9 ----------------------- Page: 10 ----------------------
SIST ISO 286-1:1999
IS0 286-l : 1988 (El
4.11.2 hole-basis. system of fits : A system of fits in which
4.103 transition fit: A fit which may provide either a
the required clearances or interferences are. obtained by
clearance or an interference between the hole and shaft when
associating shafts of various tolerance classes with holes of a
assembled, depending on the actual sizes of the hole and shaft,
single tolerance class.
i.e. the tolerance zones of the hole and the shaft overlap com-
pletely or in part (see figure IO).
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
Shaft
. . .
to the basic size, i.e. the lower deviation is zero (see figure 12).
Hole
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.
- Basic size (4.3.1)
4.11.1 shaft-basis system of fits: A system of fits in which
the required clearances or interferences are obtained by
NOTES
associating holes of various tolerance classes with shafts of a
single tolerance class.
1 The horizontal continuous lines represent the fundamental devi-
ations for holes or shafts.
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
2 The dashed lines represent the other limits and show the possibility
identical to the basic size, i.e. the upper deviation is zero (see
of different combinations between holes and shafts, related to their
figure I I).
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),
Shaft “h”
the minimum (lower) limit of size for an internal feature
(hole).
NOTE - Previously called “GO limit”.
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
NOTES material size for the feature, i.e.
1 The horizontal continuous lines represent the fundamental devi-
the minimum (lower) limit of size for an external feature
ations for holes or shafts.
(shaft),
2 The dashed lines represent the other limits and show the possibility
of different combinations between holes and shafts, related to their -
the maximum (upper) limit of size for an internal feature
grade of tolerance (e.g. G71h4, H6/h4, M5/h4).
(hole).
- Previously called “NOT GO limit”.
Figure 11 - Shaft-basis system of fits NOTE
---------------------- Page: 11 ----------------------
SIST ISO 286-1:1999
IS0 286-1 : 1988 (E)
Examples :
5 Symbols, designation and interpretation
of tolerances, deviations and fits
32H7
8OjsI5
10096
5.1 Symbols
-0 012
IO0 -0:034
5.1 .l Standard tolerance grades
ATTENTION - In order to distinguish between holes and
The standard tolerance grades are designated by the letters IT
shafts when transmitting information on equipment with
followed by a number, e.g. IJ7. When the tolerance grade is
limited character sets, such as telex, the designation shall be
associated with (a) letter(s) representing a fundamental
prefixed by the following letters:
deviation to form a tolerance class, the letters IT are omitted,
e.g. h7. -
H or h for holes;
- S or s for shafts.
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 Examples :
general use, are given in annex A for information purposes.
5OH5 becomes H5OH5 or h5Oh5
5Oh6 becomes S5OH6 or s5Oh6
5.1.2 Deviations
This method of designation shall not be on
drawings.
5.1.2.1 Position of tolerance zone
The position of the tolerance zone with respect to the zero line,
5.2.3 Fit
which is a function of the basic size, is designated by (an) upper
case letter(s) for holes (A . . . ZC) or (a) lower case letter(s) for
A fit requirement between mating features shall be designated
shafts (a . . . zc) (see figures I3 and 14).
NOTE - To avoid confusion, the following letters are not used :
a) the common basic size;
I, i; L, I; 0, 0; Q, q; W, w.
b) the tolerance class symbol for the hole;
c) the tolerance class symbol for the shaft.
5.1.2.2 Upper deviations
Examples :
The upper deviations are designated by the letters “ES” for
Ii7
52H7lg6 or 52 -
holes and the letters “es” for shafts.
ATTENTION - In order to distinguish between the hole and
5.1.2.3 Lower deviations
the shaft when transmitting information on equipment with
limited character sets, such as telex, the designation shall be
The lower deviations are designated by the letters “El” for
prefixed by the following letters:
holes and the letters “ei” for shafts.
- H or h for holes;
5.2 Designation
- S or s for shafts;
and the basic size repeated.
5.2.1 Tolerance class
Examples :
A tolerance class shall be designated by the letter(s) represent-
ing the fundamental deviation followed by the number
52H7/g6 becomes H52H7/S52G6 or h52h7/s52g6
representing the standard tolerance grade.
This method of designation shall not be used on
Examples :
drawings.
H7 (holes)
h7 (shafts)
5.3 Interpretation of a toleranced size
5.3.1 Tolerance indication in accordance with IS0 8015
5.2.2 Toleranced size
The tolerances for workpieces manufactured to drawings
A toleranced size shall be designated by the basic size followed
marked with the notation, Tolerancing IS0 8015, shall be
by the designation of the required tolerance class, or the ex-
plicit deviations. interpreted as indicated in 5.3. I. I and 5.3.1.2.
---------------------- Page: 12 ----------------------
SIST ISO 286-1:1999
Is0 286-I : 1988 (El
a) Holes (internal features)
b) Shafts (external features)
NOTES
I 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---------------------- Page: 13 ----------------------
SIST ISO 286-1:1999
60286-1:1988 E)
I-- l-
. .
. .
CL) LLJ
0 0
z z
---------------------- Page: 14 ----------------------
SIST ISO 286-1:1999
IS0 286-k 1988 a(E)
6 Graphical representation
53.1 .I Linear size tolerances
The major terms and definitions given in clause 4 are illustrated
A linear size tolerance controls only the actual local sizes (two-
in figure 15.
point measurements) of a feature, but not its form deviations
(for example circularity and straightness deviations of a cylin-
In practice, a schematic diagram such as that shown in
drical feature or flatness deviations of parallel surfaces). There
figure 16 is used for simplicity. In this diagram, the axis of the
is no control of the geometrical interrelationship of individual
workpiece, which is not shown in the figure, according to con-
features by the size tolerances. (For further information, see
vention always lies below the diagram.
ISO/R 1938 and IS0 8015.)
two deviations of the hole are
In the example illustrated, the
5.3.1.2 Envelope requirement
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 ad-
Upper deviation (4.6.1.1) -
dition to the dimension and tolerance. This indicates a mutual
Lower deviation (4.6.1.2)
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 1938 and Hole (4.2)
r r
IS0 8015.)
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.
53.2 Tolerance indication not in accordance with
IS0 6015
The tolerances for workpieces manufactured to drawings
which do not have the notation, Tolerancing IS0 6015, 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 con-
tacts 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
Minimum limit of size (4.3.3.2) -
least material limit of size.
Maximum limit of size (4.3.3.1)
b) For shafts
Basic size (4.3.1)
The diameter of the smallest perfect imaginary cylinder,
which can be circumscribed about the shaft so that it just
Figure 15 - Graphical representation
contacts the highest points of the surface, should not be
larger than the maximum material limit of size. The mini-
mum diameter at any position on the shaft shall be not less
than the least material limit of size.
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.
Unless otherwise specified, and subject to the above require-
ments, departures from a perfect cylinder may reach the full 2
value of the diameter tolerance specified. For further informa-
Shaft
tion, see ISO/R 1938.
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
Figure 16 - Simplified schematic diagram
circularity and/or straightness (see IS0 1101).
---------------------- Page: 15 ----------------------
SIST ISO 286-1:1999
IS0 286-l : 1988 (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 OC (see IS0 I). The fundamental deviations for holes and their respective sign
( + or - ) are shown in figure 18. Values for the fundamentaldeviations are given in table 3.
The upper deviation (ES) and lower deviation (H) are
8 Standard tolerances for basic sizes up to
established from the fundamental deviation and the standard
315Omm
tolerance grade (IT) as shown in figure 18.
8.1 Basis of the system
Deviations A to H Deviations K to ZC
The bases for calculating the standard tolerances are given in
(not valid for tolerance grades
annex A.
less than or equal to IT8
of deviation K and tolerance
class M8)
8.2 Values of standard tolerance grades (IT)
Values of standard tolerance grades IT1 to IT18 inclusive are
Zero line
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.
ES = negative ( - 1 funda-
EI = positive (+ 1 funda-
9 Fundamental deviations for basic sizes up
mental deviation mental deviation
to315Omm
ES = EI + IT EI = ES - IT
9.1 Fundamental deviations for shafts
[except deviation js (see 9.3)]
Figure 18 - Deviations for holes
The fundamental deviations for shafts and their respective sign
( + or - 1 are shown in figure 17. Values for the fundamental
9.3 Fundamental deviations js and JS
deviations are given in table 2.
(see figure 19)
The upper deviation (es) and lower deviation (ei) are estab-
The information given in 9.1 and 9.2 does not apply to fun-
lished from the fundamental deviation and the standard
damental deviations js and JS, which are a symmetrical
tolerance grade (IT) as shown in figure 17.
distribution of the standard tolerance grade about the zero line,
i.e. for js:
Deviations a to h Deviations k to zc IT
es = ei = -
and for JS:
ES = EI.= -
Zero line
es ES
ei = positive ( + ) funda-
es = negative ( - 1 funda-
Shaft
I Hole
mental deviation
mental deviation
ei = es - IT es = ei + IT
Figure 17 - Deviations for shafts
Deviations js and JS
Figure 19 -
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SIST ISO 286-1:1999
IS0 286-1 : 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...
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