ISO/TC 213 N 160 Date: 1997-09-19

ISO/CD 8062-2 ISO/TC 213/WG 9 Secretariat: SIS/SMS

Geometrical product specifications (GPS) - Dimensional and geometrical tolerances for moulded parts — — Part 2: Dimensional and geometrical tolerances and machining allowances for castings WARNING

This document is not an ISO standard. It is distributed for review and comment. It is subject to change withour notice and may not be referred to as an International Standard.

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ISO 1997 - All rights reserved

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Document type: International Standard Document subtype: Not applicable Document stage: (30) Committee Document language: E F:\USER\AKJ\WP51DOK\GPS\TC213WG9\8062-2.DOC ISOSTD ISO Template Version 3.0 1997-02-07

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Contents 1 Scope................................................................................................................................................................. 1 2 Normative reference(s) ..................................................................................................................................... 1 3 Definitions......................................................................................................................................................... 1 4 Tolerance grades .............................................................................................................................................. 1 4.1 Dimensional tolerance grades ...................................................................................................................... 1 4.2 Geometrical tolerance grades ....................................................................................................................... 2 4.3 Non-ridgid parts............................................................................................................................................. 5 5 Mismatch ........................................................................................................................................................... 5 6 Wall thickness................................................................................................................................................... 5 7 Tapered features............................................................................................................................................... 5 8 Position of tolerance zone ............................................................................................................................... 5 9 Required machining allowances, RMA............................................................................................................ 5 9.1 General ........................................................................................................................................................... 5 9.2 Grades of required machining allowance .................................................................................................... 8 9.3 Surfaces pre-machined by the foundry ........................................................................................................ 8 10 Indication on drawings................................................................................................................................... 8 10.1 Indication of dimensional casting tolerances ............................................................................................ 8 10.2 Indication of machining allowances ........................................................................................................... 9 10.3 Indication of geometrical casting tolerances ........................................................................................... 10 11 Machined surfaces........................................................................................................................................ 10 Annex A (informative) Casting dimensional and geometrical tolerances....................................................... 12 Annex B (informative) Casting general dimensional and geometrical tolerances ......................................... 15 Annex C (informative) Required machining allowance grades (RMA) ............................................................ 15 Annex D (informative) Symmetry (see clause 4.2) - Examples ........................................................................ 17 Annex E (informative) Concepts for general tolerancing of characteristics .................................................. 18 Annex F (informative) Former praxis (Tapered features)................................................................................. 19 Annex G (informative) Relation to the GPS matrix model ............................................................................... 20 Annex H (informative) Bibliography.................................................................................................................. 21 Copyright notice

This ISO document is a working draft and is copyright protected by ISO. While the reproduction of working drafts or committee drafts in any form for use by participants in the ISO standards development process is permitted without prior permission from ISO, neither this document nor any extract from it may be reproduced, stored or transmitted in any form for any other purpose without written permission from ISO. Requests for permission to reproduce this document for the purpose of selling it should be addressed as shown below or to ISO's member body in the country of the requester: Secretariat of ISO/TC 213

Danish Standards Association Kollegievej 6, DK-2920 Charlottenlund, Denmark Att.: Mr. Hans Henrik Køster Tel. +45 39 96 61 01 Fax +45 39 96 61 02 e-mail [email protected] Reproduction for sales purposes may be subject to royalty payments or a licensing agreement. Violators may be prosecuted.

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ISO/CD 8062-2

Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO 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. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. ISO 8062, Part 2, was prepared by Technical Committee ISO/TC 213, Dimensional and geometrical product specifications and verification. This International Standard cancels and replaces ISO 8062:1994 of which it constitutes a technical revision. Annexes A, B, C, D, E, F, G and H are for information only.

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Introduction This International Standard is a geometrical product specification (GPS) standard and is to be regarded as a general GPS standard (see ISO/TR 14683). It influences link 2 of the chain of standards on dimensional and geometrical tolerances for moulded parts. For more detailed information of the relation of this standard to other standards and the GPS matrix model see annex A. This International Standard relates to a system of tolerance grades and machining allowance grades for casts metals and their alloys. The tolerance specified for a casting may determine the casting method. It is therefore recommended, before the design or the order is finalized, that the customer liaise with the foundry to discuss a) the proposed casting design and accuracy required; b) machining requirements; c) method of casting; d) the number of castings to be manufactured; e) the casting equipment involved; f) datum target system according to ISO 5459; g) casting alloy; h) any special requirements, for instance, individual dimensional and geometrical tolerances, fillet radii tolerances and individual machining allowances; Because the dimensional and geometrical accuracy of a casting is related to production factors, tolerance grades which can be achieved for various methods and metals are described in Annex A for i) dimensional tolerances long series and mass production, where development, adjustment and maintenance of casting equipment make it possible to achieve close tolerances; j) dimensional tolerances short series and single production; k) geometrical tolerances. Information on typical required machining allowance grades is given in Annex C.

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COMMITTEE DRAFT

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Geometrical product specifications (GPS) - Dimensional and geometrical tolerances for moulded parts — — Part 2: Dimensional and geometrical tolerances and machining allowances for castings

1 Scope This part of ISO 8062 specifies a system of dimensional and geometrical tolerances as well as required machining allowance grades for castings as delivered to the purchaser. It is applicable to the dimensional and geometrical accuracy of castings in all cast metals and their alloys produced by various casting manufacturing processes [see clause 4 and Introduction h)]. This part of ISO 8062 shall apply to both general dimensional and geometrical tolerances referred to in the field of the drawing and to individual dimensional and geometrical tolerances directly specified on the drawing (see clause 10). Individual geometrical tolerances shall be indicated as specified in ISO 1101. General geometrical tolerance grades in accordance with this part of ISO 8062 should be specified when the fundamental tolerancing principle in accordance with ISO 8015 is used and indicated on the drawing (see Annex B).

2 Normative reference(s) The following standards contain provisions which, through reference is this text, constitute provisions of this international standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this international standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid international standards. ISO 1101, Technical drawings - Geometrical tolerancing - Tolerancing of form, orientation, location and runout - Generalities, definitions, symbols, indications on drawings ISO 1302, Technical drawings - Method of indicating surface texture ISO 5459, Technical drawings - Geometrical tolerancing - Datums and datum systems for geometrical tolerances ISO 8015, Technical drawings - Fundamental tolerancing principle ISO 8062-11, General terms for moulded parts ISO 129-X1, Technical drawings - Indication of linear and angular dimensions ISO 10579, Technical drawings - Dimensioning - Non-rigid parts

3 Definitions For the purpose of this International Standard, the definitions in ISO 8062-1 apply, as well as the definitions given in ISO 1101 and ISO 5459.

4 Tolerance grades 4.1 Dimensional tolerance grades There are 16 casting dimensional tolerance grades, designated CT1 to CT16 (see table 1).

1 Under preparation.

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Dimensions for which general tolerances are not suitable shall be allocated individual tolerances. See ISO 129-X (ISO 406)2) . Table 1 — Casting dimensional tolerances 1)

Raw casting basic dimensions mm

Total casting tolerance mm

over

Casting tolerance grade CT

up to and including

2) 3)

1

2

3

4

5

6

7

8

9

10

11

12

13

4)

14

4)

15

4)

16

10 16

10 16 25

0,09 0,1 0,11

0,13 0,14 0,15

0,18 0,2 0,22

0,26 0,28 0,3

0,36 0,38 0,42

0,52 0,54 0,58

0,74 0,78 0,82

1 1,1 1,2

1,5 1,6 1,7

2 2,2 2,4

2,8 3 3,2

4,2 4,4 4,6

6

8

10

12

25 40 63

40 63 100

0,12 0,13 0,14

0,17 0,18 0,2

0,24 0,26 0,28

0,32 0,36 0,4

0,46 0,5 0,56

0,64 0,7 0,78

0,9 1 1,1

1,3 1,4 1,6

1,8 2 2,2

2,6 2,8 3,2

3,6 4 4,4

5 5,6 6

7 8 9

9 10 11

11 12 14

14 16 18

100 160 250

160 250 400

0,15 -

0,22 0,24 -

0,3 0,34 0,4

0,44 0,5 0,56

0,62 0,7 0,78

0,88 1 1,1

1,2 1,4 1,6

1,8 2 2,2

2,5 2,8 3,2

3,6 4 4,4

5 5,6 6,2

7 8 9

10 11 12

12 14 16

16 18 20

20 22 25

400 630 1000

630 1000 1600

-

-

-

0,64 -

0,9 1 -

1,2 1,4 1,6

1,8 2 2,2

2,6 2,8 3,2

3,6 4 4,6

5 6 7

7 8 9

10 11 13

14 16 18

18 20 23

22 25 29

28 32 37

1600 2500 4000 6300

2500 4000 6300 10000

-

-

-

-

-

-

2,6 -

3,8 4,4 -

5,4 6,2 7 -

8 9 10 11

10 12 14 16

15 17 20 23

21 24 28 32

26 30 35 40

33 38 44 50

42 49 56 64

1) 2) 3) 4) 5)

4) 5)

See clause 8. For wall thicknesses in grade CT1 to CT15, one grade coarser applies (see clause 6). See clause 4. For sizes up to 16 mm, general tolerances from CT13 to CT16 are not available. For these sizes individual tolerances shall be indicated. Grade 16 exists only for wall thicknesses of castings generally specified to CT15.

4.2 Geometrical tolerance grades There are 7 casting geometrical tolerance grades (CTG) designated CTG 2 to 8 (see tables 2 to 5). NOTE 1

Values are not given for grade CTG 1. This grade is reserved for finer values which may be required in the future.

The nominal length to be used in tables 2 to 5 shall be the largest dimension of the considered feature. The datums to be used in tables 4 and 5 shall be the longer of the two features. If the features are of equal nominal length, either may be taken as the datum (examples, see Annex D). When geometrical casting tolerances indicated by a general geometrical tolerance grade are not suitable, individual geometrical casting tolerances shall be allocated. NOTE 2 E.

The application of general tolerances according to this standard, see clause 10, implies the concept given in Annex

Table 2 — Tolerances on straightness Raw casting nominal Total geometrical tolerance length of the feature mm 1)

mm Over

Up to and including

Casting geometrical tolerance grade (CTG)

10

2 0,08

3 0,12

4 0,18

5 0,27

6 0,4

7 0,6

8 0,9

10

30

0,12

0,18

0,27

0,4

0,6

0,9

1,4

30

100

0,18

0,27

0,4

0,6

0,9

1,4

2,0

2) Under preparation, will replace ISO 406:1987.

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100

300

0,27

0,4

0,6

0,9

1,4

2,0

3,0

300

1000

0,4

0,6

0,9

1,4

2,0

3,0

4,6

1000

3000

-

-

-

2,0

3,0

4,6

6,8

4,6 3,0 10000 3000 1) When a value is outside the table, individual tolerances shall be indicated.

6,8

10

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Table 3 — Tolerances on flatness Raw casting nominal Total geometrical tolerance length of the feature mm 1)

mm Over

Up to and including

Casting geometrical tolerance grade (CTG)

10

2 0,12

3 0,18

4 0,27

5 0,4

6 0,6

7 0,9

8 1,4

10

30

0,18

0,27

0,4

0,6

0,9

1,4

2,0

30

100

0,27

0,4

0,6

0,9

1,4

2,0

3,0

100

300

0,4

0,6

0,9

1,4

2,0

3,0

4,6

300

1000

0,6

0,9

1,4

2,0

3,0

4,6

6,8

1000

3000

-

-

-

3,0

4,6

6,8

10

6,8 4,6 10000 3000 1) When a value is outside the table, individual tolerances shall be indicated.

10

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Table 4 — Tolerances on circularity, parallelism, perpendicularity and symmetry Raw casting nominal Total geometrical tolerance length of the feature mm 1)

mm Over

Up to and including

Casting geometrical tolerance grade (CTG)

10

2 0,18

3 0,27

4 0,4

5 0,6

6 0,9

7 1,4

8 2,0

10

30

0,27

0,4

0,6

0,9

1,4

2,0

3,0

30

100

0,4

0,6

0,9

1,4

2,0

3,0

4,6

100

300

0,6

0,9

1,4

2,0

3,0

4,6

6,8

300

1000

0,9

1,4

2,0

3,0

4,6

6,8

10

1000

3000

-

-

-

4,6

6,8

10

15

3000 10000 6,8 10 1) When a value is outside the table, individual tolerances shall be indicated.

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Table 5 —Tolerances on coaxiality Raw casting nominal Total geometrical tolerance length of the feature mm 1)

mm Over

Up to and including

Casting geometrical tolerance grade (CTG)

10

2 0,27

3 0,4

4 0,6

5 0,9

6 1,4

7 2,0

8 3,0

10

30

0,4

0,6

0,9

1,4

2,0

3,0

4,6

30

100

0,6

0,9

1,4

2,0

3,0

4,6

6,8

100

300

0,9

1,4

2,0

3,0

4,6

6,8

10

300

1000

1,4

2,0

3,0

4,6

6,8

10

15

1000

3000

-

-

-

6,8

10

15

23

23

35

15 10 10000 3000 1) When a value is outside the table, individual tolerances shall be indicated.

4.3 Non-ridgid parts For drawings where the tolerances according to this standard apply in a specified restrained condition it is to be referred to ISO 10579 onthe drawing.

5 Mismatch Unless otherwise specified, mismatch shall lie within the tolerance shown in table 1. When it is important to restrict further value of mismatch, the maximum value shall be stated on the drawing (see 10.1).

6 Wall thickness Unless otherwise specified, the tolerance for wall thickness in grades CT1 to CT15 shall be one grade coarser than the general tolerance for other dimensions; for example, if there is a general tolerance on a drawing of CT10, the tolerance on wall thicknesses shall be CT11.

7 Tapered features See ISO 8062-1 and Annex F, Former praxis.

8 Position of tolerance zone The tolerance zone, unless otherwise stated, shall be symmetrically disposed with respect to a basic dimension, i.e. with one half on the positive side and one half on the negative side (see figure 1). When agreed between manufacturer and purchaser for specific reasons, the tolerance zone may be asymmetric. In such a case the tolerance shall be stated individually, following the basic dimensions.

9 Required machining allowances, RMA 9.1 General Unless otherwise specified, the required machining allowance is valid for the entire raw casting, i.e. only one value is specified for all surfaces to be machined, and this shall be selected from the appropriate dimension range according to the largest overall dimension of the finished casting after final machining (see figure 9).

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The required machining allowance and the casting tolerance shall be arranged as shown in figures 1 to 4. When applicable, the taper also shall be considered.

PLACE FIGURE HERE

R = Raw casting basic dimension F = Dimension after final machining RMA = Required machining allowance CT = Casting tolerance Figure 1 — External machining of boss

PLACE FIGURE HERE

Figure 2 — Internal machining

PLACE FIGURE HERE

Figure 3 — Machining of step dimension

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PLACE FIGURE HERE

Figure 4 — Machining on one side of feature

PLACE FIGURE HERE

Figure 5 — Largest overall dimension of the casting after final machining

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9.2 Grades of required machining allowance There are 10 grades of required machining allowance, designated A to K (see table 6). NOTE

Grades recommended for particular alloys and manufacturing methods are shown in table C.1 for information only.

Table 6 — Required machining allowances (RMA) Largest Required machining allowance dimension 1) mm mm Over Up to Required machining allowance grade and including A 2) B 2) C D E F G H J K 1,4 1 0,7 0,5 0,5 0,4 0,3 0,2 0,1 0,1 40 2 1,4 1 0,7 0,5 0,4 0,3 0,3 0,2 0,1 63 40 4 2,8 2 1,4 1 0,7 0,5 0,4 0,3 0,2 100 63 6 4 3 2,2 1,5 1,1 0,8 0,5 0,4 0,3 160 100 8 5,5 4 2,8 2 1,4 1 0,7 0,5 0,3 250 160 10 7 5 3,5 2,5 1,8 1,3 0,9 0,7 0,4 400 250 12 9 6 4 3 2,2 1,5 1,1 0,8 0,5 630 400 14 10 7 5 3,5 2,5 1,8 1,2 0,9 0,6 1000 630 16 11 8 5,5 4 2,8 2 1,4 1 0,7 1600 1000 18 13 9 6 4,5 3,2 2,2 1,6 1,1 0,8 2500 1600 20 14 10 7 5 3,5 2,5 1,8 1,3 0,9 4000 2500 22 16 11 8 5,5 4 2,8 2 1,4 1 6300 4000 24 17 12 9 6 4,5 3 2,2 1,5 1,1 10000 6300 1) Largest overall dimension of the casting, after final machining. 2) Grades A and B shall only be applied in special cases, for example with series production in which the pattern equipment, the casting procedure and the machining procedure with regard to clamping surfaces and datum surfaces or targets have been agreed between the customer and the foundry. 3) Sand casting and metallic permanent mould for steel, gray iron, S.G. iron and malleable iron of dimension of less than equal 100 mm may apply 2 - 3 larger grade of required machining allowance, when required machining allowance of this table is smaller.

9.3 Surfaces pre-machined by the foundry Any surfaces to be pre-machined by the foundry and the necessary machining allowances for the final machining shall be stipulated on the drawing by the customer in accordance with ISO 1302. The required machining allowances necessary for the achievement of the pre-machined condition shall be the responsibility of the foundry, independent of the values given in table 6.

10 Indication on drawings 10.1 Indication of dimensional casting tolerances Casting tolerances according to this International Standard shall be tested on the drawing in one of the following ways:

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a)

b)

c)

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with general information relating to tolerances; EXAMPLE ”General tolerances ISO 8062 - CT12” if further restriction of the mismatch is required (see clause 4); EXAMPLE ”General tolerances ISO 8062 - CT12 - maximum mismatch 1,5” if individual tolerances are required following the basic dimension. EXAMPLE +5 ”95 ± 3 ” or "200 − 3 "

10.2 Indication of machining allowances The surfaces to be machined, the required machining allowance value and, in brackets, the required machining allowance grade shall be stated on the drawing. These shall be taken into account when the pattern or die equipment is being produced. Required machining allowances shall be stated on the drawing as follows: a) with general information relating to tolerances and required machining allowances; EXAMPLE For a required machining allowance of 6 mm in grade H for a casting in the largest dimension range over 400 mm and up to 630 mm (with general tolerance for the casting ISO 8062 - CT12): ”ISO 8062 - CT12 - RMA 6 (H)” and/or b) on a particular surface on the drawing, if an individual required machining allowance is necessary (see 10.3). EXAMPLE See figure 6.

Figure 6 — Indication of required machining allowance on individual surfaces

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10.3 Indication of geometrical casting tolerances Geometrical casting tolerances according to this standard shall be stated on the drawing in one of the following ways: a) When general tolerances in accordance with this part of ISO 8062 apply in conjunction with the general casting tolerances in accordance with table 1, the following information shall be indicated in or near the title block: - ”ISO 8062” - the tolerance grade (CT) in accordance with table 1 and the required machining allowance (RMA) in accordance with table 6, - the tolerance grade (CTG) in accordance with table 2 to 5. EXAMPLE ”ISO 8062 - CT12 - RMA 6 (H) - CTG 7” NOTE 1 - For the concept of general tolerancing, see clause 1, Scope and Annex E, clause E.4. b) For general geometrical casting tolerances according to table 2: EXAMPLE ”ISO 8062 - CTG 7” NOTE 2 - For the concept of general tolerancing, see clause 1, Scope and Annex E, clause E.4. c) When individual geometrical tolerances are required, these may be finer or coarser than the general geometrical tolerances which would normally be applied to the nominal length of the feature, but the particular tolerance values should be chosen from table 2 to table 5: EXAMPLE For an individual geometrical casting flatness tolerance of 3 mm, e.g. with a raw casting nominal length of the feature of 500 mm and the value taken from CTG 6 in table 3.

Figure 7

11 Machined surfaces For surfaces to be machined the dimensional and geometrical deviations must allow that the finished dimensions and form can be achieved. NOTE

This can lead to a reduction of the size tolerance on the least material limit by the extracted geometrical deviation. See figure 8.

General tolerances ISO 8062 - CT 11 - RMA 5 (G) - CTG 5

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Figure 8

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Annex A (informative) Casting dimensional and geometrical tolerances

A.1 Tables A.1 and A.2 show dimensional and table A show geometrical tolerance grades which can normally be expected in casting processes. As indicated in the Introduction to this International Standard, the accuracy of a casting process is dependent upon many factors, including: a) complexity of the design; b) type of pattern equipment or die equipment; c) the metal or alloy concerned; d) the condition of patterns or dies; e) the foundry working methods. A.2 For long series of repetitive work, it may be possible to make adjustments and to control core positions carefully to achieve dimensional tolerance grades finer than those indicated in table A.1. A.3 In sand casting for short production series and for single castings, it is generally impractical and uneconomical to use metal patterns and to develop equipment and casting procedures resulting in narrow tolerances. The wider tolerances for this class of manufacture are shown in table A.2. A.4 Dimensional tolerances in table 1 are based on foundry data from a number of countries. These data were used to construct a series of smooth curves using increments of √ 2 for grades CT1 to CT13, and 3 √ 2 for grades CT13 to CT16. Many dimensions of a casting are affected by the presence of a mould joint or a core, requiring incresed dimensional tolerance. Since the designer will not necessarily be aware of the mould and core layour to be used, increases have already been included in table 1. A.5 Geometrical tolerances in table 2 and 5 are based on foundry data from a number of countries.

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ISO/CD 8062-2 Table A.1 — Casting dimensional tolerance grades for long-series production raw castings

Method

Sand cast, hand moulding Sand cast, machine moulding and shell moulding Metalllic permanent mould 3) (except pressure die casting) Pressure die casting 3) Investment casting 4) NOTES

Tolerance grade CT Casting material Steel

Grey iron

S.G. iron

Malleabl Copper e iron alloys

Zinc alloys

Light metal alloys 11 to 14 11 to 14 11 to 14 11 to 14 10 to 13 10 to 13 9 to 12

Nickelbased alloys 11 to 14

Coboltbased alloys 11 to 14

8 to 12

8 to 12

8 to 12

8 to 12

8 to 10

8 to 10

7 to 9

8 to 12

8 to 12

7 to 9

7 to 9

7 to 9

7 to 9

7 to 9

6 to 8

6 to 8

4 to 8

5 to 7 4 to 6

4 to 6

4 to 6

4 to 6

4 to 6

4 to 6

4 to 6

1) The tolerance grades indicated are those which can normally be held for castings produced in long series

and when production factors influencing the dimensional accuracy of the casting have been fully developed. 2) This International Standard can also be applied to processes and materials not cited in this table by

agreement between the producer and the user of the castings. 3)

During the life cycle of a die or metallic permanent mould the tolerance grade may be increased with 1 tolerance grade.

4)

For investment castings applies: over 100 mm grade 4 to 8 over 400 mm grade 4 to 9

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Table A.2 — Casting dimensional tolerance grades for short-series or single-production raw castings Method

Moulding material

Tolerance grade CT Casting material Steel Grey iron S.G. iron Malleabl e iron

Sand Clay13 to 15 cast, bonded handmoulded Chemically 12 to 14 bonded NOTES

Copper alloys

13 to 15

13 to 15

13 to 15

13 to 15

Light metal alloys 11 to 13

11 to 14

11 to 14

11 to 14

10 to 13

10 to 13

Nickelbased alloys 13 to 15

Coboltbased alloys 13 to 15

12 to 14

12 to 14

1)

The tolerance grades indicated are those which can normally be held for castings produced in short series or as single castings.

2)

The values in this table apply generally to basic dimensions greater than 25 mm. For smaller dimensions, finer tolerances can normally be economically and practically held as follows: basic dimension up to 10 mm: three grades finer; basic dimensions 10 mm to 16 mm: two grades finer; basic dimensions 16 mm to 25 mm: one grade finer.

a) b) c) 3)

This International Standard can also be applied to processes and materials not cited in this table by agreement between the producer and the user of the castings. Table A.3 — Casting geometrical tolerances grades

Method

Steel

Grey iron

S.G. iron

Malleabl Cu e iron alloys

Zu alloys

Light metal alloys 5 to 7

Ni based alloys 6 to 8

Co based alloys 6 to 8

Sand cast, 6 to 8 5 to 7 5 to 7 5 to 7 5 to 7 5 to 7 hand moulding 5 to 7 4 to 6 4 to 6 4 to 6 4 to 6 4 to 6 4 to 6 5 to 7 5 to 7 Sand cast, machine moulding and shell moulding 3 to 5 3 to 5 Metalllic perma1) nent mould (except pressure die casting) 2 to 4 2 to 4 2 to 4 Pressure die 1) casting Investment 4 to 6 3 to 5 3 to 5 3 to 5 3 to 5 2 to 4 3 to 5 4 to 6 4 to 6 casting 1) During the life cycle of a die or metallic permanent mould the tolerance grade may be increased with 1 tolerance grade. 2)

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For investment castings applies: over 100 mm grade 4 to 8 over 400 mm grade 4 to 9

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Annex B (informative) Casting general dimensional and geometrical tolerances

According to the principle of independency (see ISO 8015), casting general dimensional and geometrical tolerances apply independently of the extracted local size of the casting features. Accordingly, the general geometrical tolerances may be used even if the features are everywhere at their maximum material size (see figure B.1).

General tolerances ISO 8062-2 CT10-CTG 6

Figure B.1 — Principle of independency; maximum permissible deviations on the same feature NOTE

The dimensional tolerance is taken from CT 10 and the geometrical tolerances are taken from CTG 6.

When the envelope requirement E according to ISO 8015 is individually indicated adjacent to the size dimension the envelope requirement shall also be complied with.

Annex C (informative) Required machining allowance grades (RMA)

RMA grades recommended for particular metals and alloys and manufacturing methods are presented in table C.1. Table C.1 — Typical required machining allowance grades for raw castings Method

Sand cast, hand moulding Sand cast, machine moulding and shell moulding

Required machining allowance grade Casting material Steel Grey S.G. Malleabl Copper iron iron e iron alloys

Zinc alloys

G to K

F to H

F to H

F to H

F to H

F to H

E to G

E to G

E to G

E to G

F to H

Light metal alloys F to H

Nickelbased alloys G to K

Coboltbased alloys G to K

E to G

E to G

F to H

F to H

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ISO/CD 8062-2 Metallic permanent mould (except pressure die casting) Pressure die casting Investment E casting NOTES

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D to F

D to F

D to F

D to F

D to F

D to F

-

-

-

-

-

B to D

B to D

B to D

-

-

E

E

-

E

-

E

E

E

1) This International Standard can also be applied to processes and materials not cited in this table by

agreement between the producer and the user of the castings.

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Annex D (informative) Symmetry (see clause 4.2) - Examples

a) Datum: longer feature (l2)

b) Datum: longer feature (l1)

c) Datum: longer feature (l2)

d) Datum: longer feature (l1) Figure D.1 — Examples of general tolerances on symmetry (datum specified in accordance with clause 4.2)

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Annex E (informative) Concepts for general tolerancing of characteristics

E.1 General tolerances should be indicated on the drawing by reference to this part of ISO 8062 in accordance with clause 10. The values of general tolerances correspond to grades of customary foundry accuracy, the appropriate tolerance grade being selected and indicated on the drawing. E.2 For certain tolerance values, which corresponds to the customary foundry accuracy, there is usually no gain in manufacturing economy by enlarging the tolerance. In any event, foundry machinery and the usual foundry skill normally do not manufacture features with greater deviations. For example, a feature of 150 mm ± 1,8 mm diameter by 350 mm long manufactured in a foundry with a customary accuracy equal to or finer than CTG 7 contains the geometrical deviations well within 4,6 mm for circularity, 3 mm for straightness of surface elements (the values given have been taken from Tables 3 and 4). Specifying larger tolerances would be of no benefit in this particular foundry. However, if, for functional reasons, a feature requires a smaller tolerance value than the ”general tolerances”, then the feature should have the smaller tolerance indicated individually adjacent to the particular feature. This type of tolerance falls outside the scope of general tolerances. In cases where the function of a feature allows a casting tolerance equal to or larger than the general tolerance values, this should not be individually indicated, but should be stated on the drawing as described in clause 10. This type of tolerance allows full use of the concept of general tolerancing. There will be ”exceptions to the rule” where the function allows a larger tolerance than the general tolerances, and the larger tolerance will provide a gain in manufacturing economy. In these special cases, the larger casting tolerance should be indicated individually adjacent to the particular feature, e.g. the circularity tolerance of a large and thin ring. E.3 Using general tolerances leads to the following advantages: a) drawings are easier to read and thus communication is made more effective to the user of the drawing; b) the design draughtsman saves time by avoiding detailed tolerance calculations as it is sufficient only to know that the function allows a tolerance greater than or equal to the general tolerance; c) the drawing readily indicates which features can be produced by normal process capability, which also assists quality engineering by reducing inspection levels; d) those features remaining, which have individually indicated casting tolerances, will, for the most part, be those controlling features for which the function requires relatively small tolerances and which therefore may cause special effort in the production - this will be helpful for production planning and will assist quality control services in their analysis of inspection requirements; e) purchasers can negotiate orders more readily since the ”customary foundry accuracy” is known before the contract is placed; this also avoids arguments on delivery between the buyer and the supplier, since in this respect the drawing is complete. These advantages are fully obtained only when there is sufficient reliability that the general dimensional as well as geometrical tolerances and RMA will not be exceeded, i.e. when the customary foundry accuracy of the particular foundry is equal to or finer than the general tolerances indicated in the drawing. The foundry should, therefore, - determine by measurements what its customary foundry accuracy is; - accept only those drawings having general tolerances equal to or greater than its customary foundry accuracy; - determine by sampling that its customary foundry accuracy does not deteriorate (it is not the intention of the concept of general tolerancing to check every feature on every casting). Relying on undefined ”good foundry” with all its uncertainties and misunderstandings is no longer necessary with the concept of general tolerances. The general tolerances define the required accuracy of ”good foundry”. E.4 The tolerance the function allows is often greater than the general tolerance. The function of the parts is, therefore, not always impaired when the general tolerance is (occasionally) exceeded at any feature of the casting. Exceeding the general tolerance should lead to a rejection of the casting only if the function is impaired. E.5 It is not the intention of the concept of general tolerances, according to this standard, to inspect each general tolerance on each casting because it is unlikely that the general tolerance will be exceeded.

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Annex F (informative) Former praxis (Tapered features)

In ISO 8062:1994 the following clause concerning tapered features was included. It is replaced by the corresponding clause in ISO 8062-1. Where a design requires a tapered feature (e.g. feature with a draft angle), the tolerance shall be applied symmetrically along the surface (see figure 4).

Figure F.1 — Tolerance zone on tapered features The drawing shall specify generally whether the taper shall be added to, subtracted from or averaged to the material, e.g. taper +, figure 4 a) taper -, figure 4 b) taper ±, figure 4 c) Tapers for particular surfaces arranged differently from the general arrangement of taper of the drawing shall be indicated individually at the surface, e.g. For dimensions to be machined, ”taper +” shall be applied, irrespective of the general drawing specification for taper, in order that the finished dimensions can be achievable.

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Annex G (informative) Relation to the GPS matrix model

For full details about the GPS matrix model see ISO/TR 14638.

G.1 Information about the standard and its use ISO 8062-2 is a revision of ISO 8062:1994 and with an addition of values for geometrical tolerances for castings.

G.2 Position in the GPS matrix model This International standard is a General GPS standard, which influences the chain link 2 of the chain of standards on datums in the General GPS matrix, as graphically illustrated on figure G.1. GLOBAL GPS STANDARDS FUNDA-

GENERAL GPS MATRIX

MENTAL

Chain link number

1

2

Size Distance GPS

Radius Angle

STAN-

Form of line independent of datum

DARDS

Form of line dependent of datum Form of surface independent of datum Form of surface dependent of datum Orientation Location Circular run-out Total run-out Datums Roughness profile Waviness profile Primary profile Surface defects Edges

Figure G.1

G.3 Related standards The related standards are those of the chains of standards indicated in figure G.1.

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3

4

5

6

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Annex H (informative) Bibliography

[1] [2]

ISO/TR 14638:1995, Geometrical Product Specifications (GPS) - Masterplan ISO 2768-2:1989, General tolerances - Part 2: Geometrical tolerances for features without individual tolerance indications

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