Geometrical product specifications (GPS) -- Dimensional and geometrical tolerances for moulded parts

ISO 8062-4:2017 specifies general geometrical tolerances using surface profile tolerances related to a general datum system that remains on the final part. It also specifies machining allowances and draft angles (tapers) for castings in all cast metals and their alloys produced by various casting manufacturing processes. NOTE When there is no datum system (target or integral) on surfaces remaining in the final condition, this document cannot be applied.

Spécification géométrique des produits (GPS) -- Tolérances dimensionnelles et géométriques pour les pièces moulées

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Status
Published
Publication Date
30-Jul-2017
Current Stage
6060 - International Standard published
Start Date
01-May-2017
Completion Date
31-Jul-2017
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INTERNATIONAL ISO
STANDARD 8062-4
First edition
2017-07
Geometrical product specifications
(GPS) — Dimensional and geometrical
tolerances for moulded parts —
Part 4:
General tolerances for castings using
profile tolerancing in a general
datum system
Spécification géométrique des produits (GPS) — Tolérances
dimensionnelles et géométriques pour les pièces moulées —
Partie 4: Tolérances générales pour les pièces moulées par
tolérancement de profil dans un système général de références
spécifiées
Reference number
ISO 8062-4:2017(E)
ISO 2017
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ISO 8062-4:2017(E)
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© ISO 2017, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

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ii © ISO 2017 – All rights reserved
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ISO 8062-4:2017(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols .......................................................................................................................................................................................................................... 3

5 Rules .................................................................................................................................................................................................................................. 4

5.1 Rule A: Application of general tolerances for castings ......................................................................................... 4

5.2 Rule B: General surface profile tolerances ...................................................................................................................... 4

5.3 Rule C: General datum system ................................................................................................................................................... 4

5.4 Rule D: Tolerances overruling the general surface profile tolerances .................................................... 4

5.5 Rule E: Additional tolerances ..................................................................................................................................................... 5

5.6 Rule F: Machined condition [application case A c)] ................................................................................................ 5

5.7 Rule G: Required machining allowances (RMAs) ...................................................................................................... 5

5.8 Rule H: Draft angle (taper)............................................................................................................................................................ 6

6 General tolerances .............................................................................................................................................................................................. 7

7 Required machining allowances .......................................................................................................................................................... 9

8 Draft angles (tapers) .....................................................................................................................................................................................10

9 General drawing indication ....................................................................................................................................................................12

Annex A (informative) Concept of general tolerancing ..................................................................................................................14

Annex B (informative) Selection of general tolerances ..................................................................................................................16

Annex C (informative) Selection of required machining allowances (RMAs) .........................................................17

Annex D (informative) Example of using general tolerances ...................................................................................................18

Annex E (informative) Calculation of the nominal dimension of the moulded condition .........................21

Annex F (informative) Relation to the GPS matrix model ............................................................................................................24

Bibliography .............................................................................................................................................................................................................................25

© ISO 2017 – All rights reserved iii
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ISO 8062-4:2017(E)
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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO’s adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see the following

URL: w w w . i s o .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 213, Dimensional and geometrical product

specifications and verification.
A list of all parts in the ISO 8062 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved
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ISO 8062-4:2017(E)
Introduction

This document is a geometrical product specification (GPS) standard and is regarded as a

complementary process-specific tolerance standard (see ISO 14638). It influences chain link B of the

chain of standards on mouldings.

The ISO GPS matrix model given in ISO 14638 gives an overview of the ISO GPS system, of which this

document is a part. The fundamental rules of ISO/GPS given in ISO 8015 apply to this document and

the default decision rules given in ISO 14253-1 apply to specifications made in accordance with this

document, unless otherwise indicated.

For more detailed information about the relation of this document to other standards and the GPS

matrix model; see Annex F.

This document defines a system of tolerance grades, draft angle (taper) grades and machining allowance

grades for cast metals and their alloys.

ISO/TS 8062-2 states, in relation to the accumulation method where general dimensional tolerances

according to ISO 8062-3 are used, that there is not yet a clearly defined way in the context of the future

system of GPS standards to apply the rules for calculating of the final moulded part nominal dimensions

from the final machined moulded part nominal dimensions, taking into account the miscellaneous

influences.

One of the reasons for this problem is the lack of a proper workpiece datum system.

The general dimensional tolerances apply independently from each other (without a datum system). It

is difficult or even impossible to assess what the overall shape of the workpiece can become.

The general dimensional tolerances (± tolerances) of ISO 8062-3 apply not only to sizes but also to

centre distances and dimensions defining profile contours. This is in contradiction to the GPS rules

(e.g. ISO 14405-2).

Furthermore, with 3D CAD, the nominal dimensions are not always visible in the model. As the general

dimensional tolerances depend on the nominal dimensions, they cannot be used any more when only

the CAD model is available.

For these reasons, the use of ISO 8062-3 from a GPS-point of view cannot be recommended. This

document avoids the insufficiencies of ISO 8062-3 described above and is in full compliance with

the GPS rules. The general tolerances according to ISO 8062-3 are not comparable with the general

tolerances according to this document.
© ISO 2017 – All rights reserved v
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INTERNATIONAL STANDARD ISO 8062-4:2017(E)
Geometrical product specifications (GPS) — Dimensional
and geometrical tolerances for moulded parts —
Part 4:
General tolerances for castings using profile tolerancing in
a general datum system
1 Scope

This document specifies general geometrical tolerances using surface profile tolerances related to a

general datum system that remains on the final part. It also specifies machining allowances and draft

angles (tapers) for castings in all cast metals and their alloys produced by various casting manufacturing

processes.

NOTE When there is no datum system (target or integral) on surfaces remaining in the final condition, this

document cannot be applied.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 1101, Geometrical product specifications (GPS) — Geometrical tolerancing — Tolerances of form,

orientation, location and run-out

ISO 1660, Geometrical product specifications (GPS) — Geometrical tolerancing — Profile tolerancing

ISO 2692, Geometrical product specifications (GPS) — Geometrical tolerancing — Maximum material

requirement (MMR), least material requirement (LMR) and reciprocity requirement (RPR)

ISO 5458, Geometrical Product Specifications (GPS) — Geometrical tolerancing — Positional tolerancing

ISO 5459, Geometrical product specifications (GPS) — Geometrical tolerancing — Datums and datum systems

ISO 8062-1, Geometrical product specifications (GPS) — Dimensional and geometrical tolerances for

moulded parts — Part 1: Vocabulary

ISO/TS 8062-2, Geometrical product specifications (GPS) — Dimensional and geometrical tolerances for

moulded parts — Part 2: Rules

ISO 10135, Geometrical product specifications (GPS) — Drawing indications for moulded parts in technical

product documentation (TPD)

ISO 10579, Geometrical product specifications (GPS) — Dimensioning and tolerancing — Non-rigid parts

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 1101, ISO 1660, ISO 2692,

ISO 5458, ISO 5459, ISO 8062-1, ISO/TS 8062-2, ISO 10135, ISO 10579 and the following apply.

© ISO 2017 – All rights reserved 1
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ISO 8062-4:2017(E)

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
draft angle
taper

value of inclination (angle) that is added to a geometrical feature of a pattern or mould to ensure the

removal of the pattern or moulded part from the mould
[SOURCE: ISO 8062-1:2007, 2.15, modified]
3.1.1
external draft angle

draft angle (3.1) on a surface that has no opposite surface in the direction outward of the part

Note 1 to entry: See Figure 1.
3.1.2
internal draft angle

draft angle (3.1) on a surface that has an opposite surface in the direction outward of the part

Note 1 to entry: See Figure 1.
Key
α external draft angle
α internal draft angle
Figure 1 — External and internal draft angles
3.1.3
draft angle increasing the ideal model feature(s)
draft angle (3.1) which is part of the ideal model
Note 1 to entry: See Figure 3 a).
3.1.4
draft angle increasing the tolerance of feature(s)

draft angle (3.1) which is added to the ideal model and included in the tolerance zone

Note 1 to entry: See Figure 3 b).
2 © ISO 2017 – All rights reserved
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ISO 8062-4:2017(E)
3.2
general datum system RST

datum system according to ISO 5459, using the datum letters R, S, T, locking all degrees of freedom and

used for the general tolerance
Note 1 to entry: See Figure D.2.

Note 2 to entry: It is recommended to use a datum target system RST; see Figure D.1.

Note 3 to entry: The datum letters R, S, T, are reserved for the general datum system; see Rule C.

4 Symbols
Symbol Description Source
moulded surface
machined surface ISO 1302
moulded or machined surface
surface profile tolerance
positional tolerance
ISO 1101
theoretically exact dimension
datum of datum target
ISO 5459
datum target, fixed, moveable
5.2, 5.3
general tolerance
parting surface
ISO 10135
moveable
parting surface
fixed
draft angle increasing the ideal model feature(s) ISO 10135
draft angle increasing the tolerance of feature(s) 5.8
moulded condition
intermediate (pre)machined
ISO/TS 8062-2
final machined
provided by supplier
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ISO 8062-4:2017(E)
5 Rules
5.1 Rule A: Application of general tolerances for castings

The general tolerances for castings according to this document may be used on drawings showing:

a) the moulded condition only (see Figure D.2);

b) the premachined condition and referring to the general tolerances for castings for the features

remaining as moulded;

c) the final machined condition and referring to the general tolerances for the moulded condition

(before machining).

Prerequisite is a general datum system RST on surfaces remaining as moulded; see Rule C.

5.2 Rule B: General surface profile tolerances

The general tolerances according to this document are any surface profile tolerances related to a

general datum system RST according to ISO 5459; see Rule C. The general tolerance is to be indicated in

or near the drawing title block.

The general surface profile tolerance applies to all surfaces with the exception of Rule D.

5.3 Rule C: General datum system
A general datum system RST shall be indicated in the drawing.

When a general datum system RST is used, established by datum targets (preferred method), the

general profile tolerances according to Table 1 apply also to the datum features, if not otherwise

indicated.

When an integral general datum system RST is used, established by integral features, the general

profile tolerances according to Table 1 do not apply to the datum features. In such cases, the datum

features shall be toleranced separately by:
— an unrelated profile (form) tolerance for the primary datum;
— a profile tolerance related to the primary datum for the secondary datum;

— a profile tolerance related to the primary and to the secondary datum for the tertiary datum.

NOTE When there is no datum system (target or integral) on surfaces remaining in the final condition, this

document cannot be applied.
5.4 Rule D: Tolerances overruling the general surface profile tolerances

Individually indicated surface profile tolerances for location according to ISO 1101 and ISO 1660 and

individually indicated positional tolerances according to ISO 5458, each related directly or indirectly to

the general datum system RST and locking all degrees of freedom, overrule the general surface profile

tolerances. See Figure 2.
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ISO 8062-4:2017(E)
Key
Directly related to the general datum system RST.
Indirectly related to the general datum system RST.

Figure 2 — Individually indicated locational tolerances overruling the general tolerance

When positional tolerances for sizes are used, the (dimensional) size tolerance shall be specified in

addition either by individual indication or by reference to general tolerances.
5.5 Rule E: Additional tolerances

Other tolerances than those described in rules B and D, i.e. not related to the general datum system RST,

apply in addition to the general tolerances as further constraints.
5.6 Rule F: Machined condition [application case A c)]
The final machined condition shall be possible to be achieved.

When the tolerances for the machined surfaces are related to a datum or datum system different from

the general datum system RST, additional material is needed for the moulded condition.

Due to the inclination and offset of the general datum system RST of the moulded condition relative

to the datum system of the machined condition, the amount of additional material shall be calculated

from the geometrical tolerance of the datum surfaces of the machined condition relative to the general

datum system RST.
5.7 Rule G: Required machining allowances (RMAs)

Surfaces to be machined require a machining allowance RMA. The RMA shall be selected from Table 3

and shall be indicated on the drawing. For information on the selection of RMAs; see Annex C.

The same RMA applies to all surfaces to be machined, unless a different RMA is individually indicated

to a specific surface (according to ISO 1302).

Annex E gives examples for the calculation of the dimension of the moulded condition (raw dimension).

© ISO 2017 – All rights reserved 5
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ISO 8062-4:2017(E)
5.8 Rule H: Draft angle (taper)
The parting surface shall be indicated by the symbols and in accordance with
ISO 10135.
There are three possible ways to indicate a draft angle (taper):
a) as already included in the ideal model or drawing outlines;
b) by the symbol ;
c) by the symbol .

In case a), the general surface profile tolerance zone is located symmetrically to the nominal surface

that includes the draft angles (tapers).

In case b), the general surface profile tolerance zone is located symmetrically to the surface when the

draft angles (tapers) are added to the nominal model which excludes the draft angles in the tolerance

zone; see Figure 3 a).

In case c), the general surface profile tolerance zone increases steadily as shown in Figure 3 b).

NOTE The rules for the indication of the symbols are given in ISO 10135.

When the draft angles (tapers) are already included in the nominal model or in the drawing outlines,

“Draft angles included” shall be indicated in or near the drawing title block.
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ISO 8062-4:2017(E)

a) Draft angle increasing the ideal model b) Draft angle increasing the tolerance of

feature(s) feature(s)
Figure 3 — Draft angles
Unless otherwise indicated, draft angle plus (taper plus) (TP) shall apply.
...

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