Geometrical product specifications (GPS) -- Surface texture: Profile

This document specifies the rules for indication of surface texture by profile methods in technical product documentation by means of graphical symbols. This document does not cover population requirements. NOTEÂ Â Â Â Â Â See ISO 18391 for population (batch) specifications.

Spécification géométrique des produits (GPS) -- État de surface: Méthode du profil

Le présent document spécifie les règles d'indication des états de surface par des méthodes de profil dans la documentation technique des produits au moyen de symboles graphiques. Le présent document ne couvre pas les exigences de population. NOTE           Voir la norme ISO 18391 pour les spécifications de la population (lot).

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Published
Publication Date
19-Dec-2021
Current Stage
5060 - Close of voting Proof returned by Secretariat
Start Date
27-Oct-2021
Completion Date
26-Oct-2021
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FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 21920-1
ISO/TC 213
Geometrical product specifications
Secretariat: BSI
(GPS) — Surface texture: Profile —
Voting begins on:
2021-08-31
Part 1:
Voting terminates on:
Indication of surface texture
2021-10-26
Spécification géométrique des produits (GPS) — État de surface:
Méthode du profil —
Partie 1: Indication des états de surface
ISO/CEN PARALLEL PROCESSING
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 21920-1:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 21920-1:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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Published in Switzerland
ii © ISO 2021 – All rights reserved
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ISO/FDIS 21920-1:2021(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

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

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

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

4 Tolerance acceptance rules ....................................................................................................................................................................... 1

4.1 General ........................................................................................................................................................................................................... 1

4.2 Maximum tolerance acceptance rule ................................................................................................................................... 2

4.3 16 % tolerance acceptance rule ............................................................................................................................................... 2

4.4 Median tolerance acceptance rule.......................................................................................................................................... 2

5 Specification elements for indication of profile surface texture specifications .................................3

5.1 General ........................................................................................................................................................................................................... 3

5.2 Mandatory indication to be explicitly specified ......................................................................................................... 3

5.3 Optional indications to specify non-default or further requirements .................................................... 3

6 Indication of profile surface texture ................................................................................................................................................ 4

6.1 General ........................................................................................................................................................................................................... 4

6.2 Graphical symbols ................................................................................................................................................................................ 4

6.3 Minimal indication ............................................................................................................................................................................... 5

6.3.1 General...................................................................................................................................................................................... 5

6.3.2 Minimal indication for parameters with defined defaults ........................................................... 5

6.3.3 Minimal indication for parameters without defined defaults .................................................. 5

6.4 Complete indication............................................................................................................................................................................ 6

6.4.1 General...................................................................................................................................................................................... 6

6.4.2 Complete indication for evaluation length R-parameters ............................................................ 6

6.4.3 Complete indication for section length R-parameters .................................................................... 7

6.4.4 Complete indication for evaluation length P-parameters and W-parameters ............ 8

6.4.5 Complete indication for section length P-parameters and W-parameters .................... 9

7 Rules for indication of profile surface texture specifications ............................................................................10

7.1 General ........................................................................................................................................................................................................10

7.2 Graphical symbol for the indication of profile surface texture specifications ..............................10

7.3 Profile surface texture parameter .......................................................................................................................................11

7.4 Tolerance limit value of the profile surface texture parameter .................................................................11

7.5 Tolerance types ....................................................................................................................................................................................11

7.6 Tolerance acceptance rule ..........................................................................................................................................................11

7.7 Profile S-filter type ............................................................................................................................................................................11

7.8 Profile S-filter nesting index .....................................................................................................................................................11

7.9 Profile L-filter type (for R-parameter) or profile S-filter type (for W-parameter) ....................11

7.10 Profile L-filter nesting index (for R-parameter) or profile S-filter nesting index (for

W-parameter) ........................................................................................................................................................................................12

7.11 Evaluation length ...............................................................................................................................................................................12

7.12 Section length ........................................................................................................................................................................................12

7.13 Number of sections ..........................................................................................................................................................................12

7.14 Profile F-operator association method and element ...........................................................................................12

7.15 Profile F-operator nesting index ...........................................................................................................................................12

7.16 Method of profile extraction .....................................................................................................................................................12

7.17 Other requirements, OR(n) .......................................................................................................................................................13

7.18 Manufacturing process..................................................................................................................................................................13

7.19 Surface lay and direction of lay ..............................................................................................................................................13

7.20 Profile direction ..................................................................................................................................................................................13

7.21 Setting class, Scn .................................................................................................................................................................................13

8 Position on technical product documentation ...................................................................................................................13

© ISO 2021 – All rights reserved iii
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ISO/FDIS 21920-1:2021(E)

8.1 General ........................................................................................................................................................................................................13

8.2 Position and orientation of the graphical symbol..................................................................................................14

9 Simplified and additional indications .........................................................................................................................................17

9.1 Simplified indications ....................................................................................................................................................................17

9.1.1 General...................................................................................................................................................................................17

9.1.2 General tolerances .......................................................................................................................................................17

9.1.3 Indication by the graphical symbol combined with a letter ....................................................18

9.2 Restrictive specifications ............................................................................................................................................................19

9.3 Indication of identical specifications for a number of feature elements ...........................................20

9.4 Indication of surface lay and direction of lay .............................................................................................................20

9.4.1 General...................................................................................................................................................................................20

9.4.2 Indication of surface lay without a reference ......................................................................................21

9.4.3 Indication of surface lay and direction of lay relative to a workpiece feature .........21

9.5 Indication of the profile direction .......................................................................................................................................22

9.5.1 General...................................................................................................................................................................................22

9.5.2 Indication of the profile direction relative to the predominant direction of

the surface lay .................................................................................................................................................................22

9.5.3 Indication of the profile direction relative to a workpiece feature ...................................23

9.6 Indication of bilateral surface profile tolerances ...................................................................................................24

9.7 Indication of different requirements for several additional processes on one

surface feature ......................................................................................................................................................................................24

Annex A (normative) Proportions and dimensions of graphical symbols .................................................................25

Annex B (normative) Filter symbols for profile surface texture ..........................................................................................27

Annex C (normative) Symbols for association methods and association elements .........................................28

Annex D (informative) Indications for unambiguous surface profile specification .........................................29

Annex E (normative) Inspection procedure for the 16 % tolerance acceptance rule ....................................41

Annex F (informative) Criteria for the use of the maximum tolerance acceptance rule as the

default ...........................................................................................................................................................................................................................42

Annex G (informative) New issues and changes to previous documents.....................................................................43

Annex H (informative) Overview of profile and areal standards in the GPS matrix model ......................45

Annex I (informative) Relation to the GPS matrix model .............................................................................................................46

Bibliography .............................................................................................................................................................................................................................47

iv © ISO 2021 – All rights reserved
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ISO/FDIS 21920-1:2021(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 of 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 www .iso .org/

iso/ foreword .html.

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

specifications and verification, in collaboration with the European Committee for Standardization (CEN)

Technical Committee CEN/TC 290, Dimensional and geometrical product specification and verification, in

accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).

This document cancels and replaces ISO 1302:2002, which has been technically revised. In addition to

the change of number, the main changes to ISO 1302:2002 are as follows:
— New specification elements for indication are defined.

— The maximum tolerance acceptance rule is the default tolerance acceptance rule.

A list of all parts in the ISO 21920 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO 2021 – All rights reserved v
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ISO/FDIS 21920-1:2021(E)
Introduction

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

GPS standard (see ISO 14638). It influences chain link A of the chains of standards on profile surface

texture.

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 the specifications made in accordance with this

document, unless otherwise indicated.

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

model, see Annex H, Table H.1, and Annex I.
This document covers the indication of profile surface texture.
vi © ISO 2021 – All rights reserved
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 21920-1:2021(E)
Geometrical product specifications (GPS) — Surface
texture: Profile —
Part 1:
Indication of surface texture
1 Scope

This document specifies the rules for indication of surface texture by profile methods in technical

product documentation by means of graphical symbols.
This document does not cover population requirements.
NOTE See ISO 18391 for population (batch) specifications.
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 21920-2, Geometrical product specifications (GPS) — Surface texture: Profile — Part 2: Terms,

definitions and surface texture parameters

ISO 21920-3, Geometrical product specifications (GPS) — Surface texture: Profile — Part 3: Specification

operators

ISO 81714-1, Design of graphical symbols for use in the technical documentation of products — Part 1:

Basic rules
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 21920-2 and ISO 21920-3

apply.

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

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Tolerance acceptance rules
4.1 General

Tolerance acceptance rules define how the tolerance limits are applied to the measured parameter

values. For profile surface texture, three tolerance acceptance rules can be indicated. See ISO 21920-3:

2021, Table 1 for the position of the measurements.
1) Under preparation. Stage at the time of publication: ISO/FDIS 21920-2:2021.
2) Under preparation. Stage at the time of publication: ISO/FDIS 21920-3:2021.
© ISO 2021 – All rights reserved 1
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ISO/FDIS 21920-1:2021(E)
4.2 Maximum tolerance acceptance rule

The maximum tolerance acceptance rule does not allow any measured value to exceed the tolerance

limit. The symbol of the maximum tolerance acceptance rule is shown in Figure 1.
Figure 1 — Symbol of the maximum tolerance acceptance rule

The maximum tolerance acceptance rule is the default case and valid with or without indication of the

‘Tmax’ symbol.

NOTE 1 The suffix ‘max’ can be interpreted as the required maximal conformity of the measured value.

NOTE 2 The ‘Tmax’ symbol can be used to prevent misinterpretation of a specification.

4.3 16 % tolerance acceptance rule

A specified 16 % tolerance acceptance rule allows at most 16 % of all measured values of a parameter to

violate the tolerance limit. The symbol of the 16 % tolerance acceptance rule is shown in Figure 2.

The 16 % tolerance acceptance rule shall be applied as specified in Annex E.
Figure 2 — Symbol of the 16 % tolerance acceptance rule

The 16 % tolerance acceptance rule is valid for the parameter on the line where the ‘T16 %’ symbol is

indicated.

If a bilateral tolerance is specified in one line, 16 % of all measured values may violate the upper

tolerance limit and 16 % of all measured values may violate the lower tolerance limit.

NOTE 1 The 16 % tolerance acceptance rule defines how tolerance limits are applied to the measured values.

NOTE 2 In ISO 1302, the 16 % tolerance acceptance rule was called the 16 % rule.

NOTE 3 In contrast to ISO 1302, the 16 % tolerance acceptance rule is not the default (see Annex F for

additional information).
NOTE 4 See ISO 21920-3: 2021, Table 1 for the distribution of the measurements.
4.4 Median tolerance acceptance rule

If a median tolerance acceptance rule is specified, the median value of all measured values of a

parameter shall meet the tolerance limits. The symbol of the median tolerance acceptance rule is shown

in Figure 3.
Figure 3 — Symbol of the median tolerance acceptance rule

The median tolerance acceptance rule is valid for the parameter on the line where the ‘Tmed’ symbol is

indicated.
2 © ISO 2021 – All rights reserved
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ISO/FDIS 21920-1:2021(E)

At least three measured values shall be used to apply the median acceptance rule. A higher number of

measurements can be specified in “other requirements” (symbol OR(n), see 7.17).

NOTE 1 The median tolerance acceptance rule defines how tolerance limits are applied to the measured

values.

NOTE 2 If the median value of all measured values of a parameter meets the tolerance limit, no more than half

the measured values exceed the tolerance limit.

5 Specification elements for indication of profile surface texture specifications

5.1 General

Indications of profile surface texture specify requirements on the surface of a workpiece as well as the

specification operator.

NOTE All specification elements permitted for indication of profile surface texture specifications are listed

in 5.2 and 5.3 and described in Clause 7.
5.2 Mandatory indication to be explicitly specified
— Graphical symbol for profile surface tolerance.
— Symbol of the profile surface texture parameter.
— Tolerance limit of the profile surface texture parameter.

— For parameters without defined defaults: indication of the profile L-filter nesting index N for

R-parameters or profile S-filter nesting index N for W-parameters or the setting class Scn.

NOTE 1 Parameters without defined default are not listed in ISO 21920-3: 2021, Tables 3 to 6.

NOTE 2 The indication of the nesting index or the setting class is optional for all parameters listed in

ISO 21920-3: 2021, Tables 3 to 6.

NOTE 3 It is the responsibility of the designer to choose and indicate the appropriate L-filter or S-filter.

ISO 21920-3: 2021, Tables 3 to 6 define defaults that can be used for surfaces without particular performance

requirements.

NOTE 4 A cut-off wavelength for a profile filter is an example of a nesting index, see ISO 21920-2.

5.3 Optional indications to specify non-default or further requirements
— Tolerance type (upper, lower or bilateral tolerance limit).
— Symbol ‘T16 %’, ‘Tmax’ or ‘Tmed’ to specify a tolerance acceptance rule.
— Profile S-filter type.
— Profile S-filter nesting index.

— Profile L-filter type for R-parameters or profile S-filter type for W-parameters.

— Profile L-filter nesting index N for R-parameters or profile S-filter nesting index N for W-parameters.

ic ic

— Evaluation length l for the evaluation length parameters. Section length l and number of sections

e sc
n for the section length parameters.
— Profile F-operator association method and element.
— Profile F-operator nesting index.
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ISO/FDIS 21920-1:2021(E)
— Method of profile extraction.
— Symbol ‘OR(n)’ to specify other requirements.
— Manufacturing process.
— Surface lay and direction of lay.
— Profile direction.
— Symbol ‘Scn’ to specify a setting class.
NOTE Default settings are defined in ISO 21920-3.
6 Indication of profile surface texture
6.1 General

Profile surface texture requirements in technical product specifications shall be specified by one of the

graphical symbols described in 6.2.

A minimal indication of profile surface texture shall be built up of the graphical symbol, the parameter

designation and the parameter tolerance limit value, see 6.3.

If several parameters are specified, the parameter in the first line is relevant for the determination of

default settings (see ISO 21920-3).
All indicated specification elements are separated by a single blank character.
NOTE 1 Exceptions are defined in 9.1.

NOTE 2 See Annex G, Table G.1, for new issues in this document and changes to previous documents.

6.2 Graphical symbols

The form of the graphical symbols contains requirements for the production process. Proportions of

the graphical symbols shall be indicated as specified in Annex A.

NOTE 1 See Figure 4 for the layout of the three defined graphical symbols and their interpretation.

NOTE 2 The bar above the symbol is to distinguish this symbol from the ones used in ISO 1302 and those used

for indication of areal surface texture specifications.
a) Any manufacturing process permitted
b) Material shall be removed
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ISO/FDIS 21920-1:2021(E)
c) Material removal is not permitted
Figure 4 — Graphical symbols indicating profile surface texture
6.3 Minimal indication
6.3.1 General

If a minimal indication is specified, all defaults shall be applied. Because defaults cannot be defined for

all parameters, the minimal indication is different for parameters with and without defined defaults.

6.3.2 Minimal indication for parameters with defined defaults

Figure 5 shows all symbols and indications mandatory for a minimal indication of profile surface

texture requirements and parameters with defined defaults.
Key
a symbol for parameter
b tolerance limit value of the surface texture parameter
< > placeholder has to be specified

Figure 5 — Minimal indication for parameter with defined defaults (all defaults apply)

NOTE 1 Parameters with defined defaults are Rz, Ra, Rp, Rv, Rq, Rmax, Rt and Pt, see ISO 21920-3: 2021,

Tables 3 to 6.
NOTE 2 Exceptions are defined in 9.1.
NOTE 3 See Annex D for examples and additional information.
6.3.3 Minimal indication for parameters without defined defaults

Figure 6 shows all symbols and indications mandatory for a minimal indication of profile surface

texture requirements and parameters without defined defaults. All defaults are defined by the

mandatory specified setting class (Scn) or by one of the default values of the mandatory profile L-filter

nesting index N for R-parameters or profile S-filter nesting index N for W-parameters.

ic ic
Oblique strokes, “/”, are used to separate the specification sections.
© ISO 2021 – All rights reserved 5
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