ISO 21920-1:2021
(Main)Geometrical product specifications (GPS) — Surface texture: Profile — Part 1: Indication of surface texture
Geometrical product specifications (GPS) — Surface texture: Profile — Part 1: Indication of surface texture
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.
Spécification géométrique des produits (GPS) — État de surface: Méthode du profil — Partie 1: Indication des états de surface
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).
General Information
Relations
Standards Content (Sample)
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
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DOCUMENTATION.
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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
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ISO/FDIS 21920-1:2021(E)
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© ISO 2021
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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
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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
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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.
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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.
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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.
1)
ISO 21920-2, Geometrical product specifications (GPS) — Surface texture: Profile — Part 2: Terms,
definitions and surface texture parameters
2)
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.
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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.
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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
ic
R-parameters or profile S-filter nesting index N for W-parameters or the setting class Scn.
ic
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.
sc
— 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.
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