SIST EN ISO 21920-1:2022

SLOVENSKI STANDARD
oSIST prEN ISO 21920-1:2020
01-april-2020
Specifikacija geometrijskih veličin izdelka (GPS) - Tekstura površine: profil - 1. del:
Označevanje površinskih tekstur (ISO/DIS 21920-1:2020)
Geometrical product specifications (GPS) - Surface texture: Profile - Part 1: Indication of
surface texture (ISO/DIS 21920-1:2020)
Geometrische Produktspezifikation (GPS) - Oberflächenbeschaffenheit: Profile - Teil 1:
Angabe der Oberflächenbeschaffenheit (ISO/DIS 21920-1:2020)
Spécification géométrique des produits (GPS) - État de surface: Méthode du profil -
Partie 1: Indication des états de surface (ISO/DIS 21920-1:2020)
Ta slovenski standard je istoveten z: prEN ISO 21920-1
ICS:
17.040.20 Lastnosti površin Properties of surfaces
17.040.40 Specifikacija geometrijskih Geometrical Product
veličin izdelka (GPS) Specification (GPS)
oSIST prEN ISO 21920-1:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 21920-1:2020

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oSIST prEN ISO 21920-1:2020
DRAFT INTERNATIONAL STANDARD
ISO/DIS 21920-1
ISO/TC 213 Secretariat: BSI
Voting begins on: Voting terminates on:
2020-02-19 2020-05-13
Geometrical product specifications (GPS) — Surface
texture: Profile —
Part 1:
Indication of surface texture
Spécification géométrique des produits (GPS) — État de surface: Méthode du profil —
Partie 1: Indication des états de surface
ICS: 17.040.40
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 21920-1:2020(E)
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 SUPPORTING DOCUMENTATION. ISO 2020

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oSIST prEN ISO 21920-1:2020
ISO/DIS 21920-1:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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oSIST prEN ISO 21920-1:2020
ISO/DIS 21920-1:2020(E)
Contents
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 . 1
4.3 16% tolerance acceptance rule . 2
4.4 Median tolerance acceptance rule . 2
5 Criteria for indication of profile surface texture . 3
5.1 General . 3
5.2 Mandatory indication to be explicitly specified . 3
5.3 Optional indication to specify default deviating requirements . 3
6 Indication of profile surface texture . 4
6.1 General . 4
6.2 Graphical symbol . 4
6.3 Minimal indication . 5
6.3.1 General . 5
6.3.2 Minimal indication for parameter with defined defaults . 5
6.3.3 Minimal indication for functional parameter and parameter without defined
defaults . 5
6.4 Complete indication . 6
6.4.1 General . 6
6.4.2 Complete indication for non section length based R- parameter . 7
6.4.3 Complete indication for section length based R- parameter . 8
6.4.4 Complete indication for non section length based P- and W- parameter . 9
6.4.5 Complete indication for section length based P- and W- parameter . 10
7 Determinations for the indication of profile surface texture . 10
7.1 General . 10
7.2 Graphical symbol for surface tolerance . 11
7.3 Surface profile parameter . 11
7.4 Limit of surface parameter . 11
7.5 Tolerance types . 11
7.6 Profile s-filter type . 11
7.7 Profile s- filter nesting index . 11
7.8 Profile L-filter type (for R-parameter) or profile S-filter type (for W-parameter) . 12
7.9 Profile L- filter nesting index (for R- parameter) or profile S-filter nesting index (for
W-parameter) . 12
7.10 Evaluation length . 12
7.11 Section length . 12
7.12 Number of sections . 12
7.13 Profile F-operator type . 12
7.14 Profile F-operator nesting index . 13
7.15 Method of profile extraction . 13
7.16 Profile direction . 13
7.17 Symbol ‘OR(n)’ to specify other requirements . 13
7.18 Symbol ‘Scn’ . 13
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oSIST prEN ISO 21920-1:2020
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7.19 Symbol ‘Tmax’ . 14
7.20 Symbol ‘T16%’ . 14
7.21 Symbol ‘Tmed’ . 14
7.22 Surface lay and direction of lay . 14
7.23 Manufacturing process . 14
8 Position on technical product documentation . 14
8.1 General . 14
8.2 Position and orientation of the graphical symbol . 14
9 Additional and simplified indications . 18
9.1 Restrictive specifications . 18
9.2 Identical specifications of a number of identical feature elements . 18
9.3 Indication of the profile direction relatively to a workpiece feature . 19
9.4 Indication of bilateral surface profile tolerances . 20
9.5 Simplified indications . 20
9.5.1 General . 20
9.5.2 Majority of features with identical requirements . 20
9.5.3 Indication by the graphical symbol combined with a letter . 21
9.6 Indication of different requirements for several, additional stages of a feature . 21
Annex A (normative) Proportions and dimensions of graphical symbols . 23
A.1 General requirements . 23
A.2 Proportions . 23
A.3 Dimensions . 24
Annex B (normative) Graphical symbols for the indication of surface lay or direction of lay . 25
Annex C (normative) Graphical symbols for the indication of the profile direction . 26
Annex D (normative) Filter symbols for profile surface texture. 27
Annex E (normative) Non-filter association (F-operator) symbols . 28
Annex F (informative) Indications for unambiguous surface profile specification . 29
F.1 Examples for R-parameter specifications . 30
F.2 Examples for W-parameter specifications . 40
F.3 Examples for P-parameter specifications . 43
F.4 Examples for several parameter specifications . 46
Annex G (normative) Use of the 16% tolerance acceptance rule . 47
Annex H (informative) Criteria for the use of the Tmax tolerance acceptance rule as a
default . 48
Annex I (informative) New and changed issues to former versions . 49
Annex J (informative) Relation with the GPS matrix . 51
J.1 General . 51
J.2 Information about this part of ISO 21920 and its use . 51
J.3 Position in the GPS matrix model . 51
J.4 Related International Standards . 51
Bibliography . 52

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oSIST prEN ISO 21920-1:2020
ISO/DIS 21920-1:2020(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 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:
www.iso.org/iso/foreword.html.
The committee responsible for this document is Technical Committee ISO/TC 213, Dimensional and
geometrical product specifications and verification.
This edition cancels and replaces the edition of ISO 1302:2002, which has been technically revised.
The main changes compared to the edition of ISO 1302:2002 are as follows:
- new criteria for indication are defined
- Tmax rule is the default tolerance acceptance rule
A list of all parts in the ISO 21920 series can be found on the ISO website.

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oSIST prEN ISO 21920-1:2020
ISO/DIS 21920-1:2020(E)
Introduction
This part of ISO 21920 is a geometrical product specification (GPS) standard and is to be regarded as a
general GPS standard (see ISO 14638). It influences the chain link C of the chains of standards on profile
and areal surface texture.
The ISO/GPS matrix model given in ISO 14638 gives an overview of the ISO/GPS system of which this
part of ISO 21920is a part. The fundamental rules of ISO/GPS given in ISO 8015 apply to this part of
ISO 21920 and the default decision rules given in ISO 14253-1 apply to the specifications made in
accordance with this part of ISO 21920, unless otherwise indicated.
For more detailed information of the relation of this part of ISO 21920 to other standards and the GPS
matrix model, see Annex J.
This part of ISO 21920 covers the indication of profile surface texture.

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oSIST prEN ISO 21920-1:2020
ISO/DIS 21920-1:2020(E)
Geometrical product specifications (GPS) — Surface texture:
Profile — Part 1: Indication of surface texture
1 Scope
This part of ISO 21920 specifies the rules for indication of profile surface texture in technical product
documentation by means of graphical symbols. The indications of profile surface texture define
requirements to the surface of a workpiece as well as the measurands for verification.
This part of ISO 21920 is only valid for profile surface texure requirements based on a single workpiece.
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 21920-2:2019 Geometrical product specifications (GPS) — Surface texture: Profile — Part 2: Terms,
definitions and surface texture parameters
ISO 21920-3:2019 Geometrical product specifications (GPS) — Surface texture: Profile — Part 3:
Specification operators
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 http://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
4 Tolerance acceptance rules
4.1 General
Tolerance acceptance rules define the process of approval of a workpiece regarding its tolerance limits
due to the measured value(s) of parameter(s). For profile surface texture three tolerance acceptance
rules can be indicated.
4.2 Maximum tolerance acceptance rule
The maximum tolerance acceptance rule does not allow the tolerance limit of a parameter to be
exceeded. The symbol of the Maximum tolerance acceptance rule is shown in Figure 1.
Tmax
Figure 1 — Symbol of the maximum tolerance acceptance rule
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oSIST prEN ISO 21920-1:2020
ISO/DIS 21920-1:2020(E)
The maximum tolerance acceptance rule is the default case and valid with or without indication of the
‘Tmax’ symbol.
NOTE: The ‘Tmax’ symbol can be used for a higher clarity of a specification
4.3 16% tolerance acceptance rule
A specified 16% tolerance acceptance rule allows at most approximately 16 % of all measured values of
a parameter to exceed the tolerance limit. The symbol of the 16% tolerance acceptance rule is shown in
Figure 2.
The use of the 16% tolerance acceptance rule and the required number of measurements are defined in
Annex G.
T16%
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 approximately 16 % of all measured values may violate
the upper limit and approximately 16 % of all measured values may violate the lower limit.
NOTE 1: The 16% tolerance acceptance rule is an instruction for the approval of a workpiece based on
measured values regarding its tolerance limits.
NOTE 2: In former versions the 16% tolerance acceptance rule was named as simplified 16% rule.
NOTE 3: In contrast to former versions the 16% tolerance acceptance rule is not the default case (see
Annex H for background)
4.4 Median tolerance acceptance rule
If a median tolerance acceptance rule is specified the median value of all measured values of a
parameter has to meet the tolerance limits. The symbol of the Tmed tolerance acceptance rule is shown
in Figure 3.
Tmed
Figure 3 — Symbol of the median tolerance acceptance rule
The Tmed tolerance acceptance rule is valid for the parameter on the line where the ‘Tmed’ symbol is
indicated.
NOTE 1: The median tolerance acceptance rule is an instruction for the approval of a workpiece based
on measured values regarding its tolerance limits.
NOTE 2: If the median value of all measured values of a parameter meets the tolerance limits the
number of measured values violating the limit(s) is not determined.
NOTE 3: The use of the median tolerance acceptance rule requieres a minimal number of three
measured values of a parameter. A higher number of measurements can be specified by the
OR(n) requirements.
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oSIST prEN ISO 21920-1:2020
ISO/DIS 21920-1:2020(E)
5 Criteria for indication of profile surface texture
5.1 General
Indications of profile surface texture define requirements on the surface of a workpiece as well as the
measurands for verification.
NOTE: All criteria permitted for indications of profile surface texture are listed in Clauses 5.2 to 5.4 and
described in Clause 7.
5.2 Mandatory indication to be explicitly specified
- Graphical symbol for profile surface tolerance
- Symbol of the surface profile parameter
- For functional parameter and for all parameter without defined defaults: indication of the
profile L-filter nesting index for R- parameters or profile S-filter nesting index for W-
parameters or the setting class number
- Limit of the surface profile parameter
NOTE 1: The indication of the nesting index or the setting class number is optional for all parameter listed in
Table 3 or Table 6 of ISO 21920-3.
NOTE 2: It is the task of the design office to choose and indicate the functionally valid L-filter or S-filter
according to erlier experience or performed testing results. The Tables 3 to 6 in ISO 21920-3 are
based on extensive experience and define defaults on surfaces with low or normal functional
requirements.
5.3 Optional indication to specify default deviating requirements
- Tolerance type (upper, lower or bilateral tolerance limit)
- profile S-filter type
- profile S-filter nesting index
- profile L-filter type for R- parameter or profile S-filter type for W- parameter
- profile L-filter nesting index for R- parameter or profile S-filter nesting index for W- parameter
- evaluation length or for section length based parameter: section length and number of sections
- profile F-operator type and method
- profile F-operator nesting index
- Method of profile extraction
- Profile direction
- Symbol ‘OR(n)’ to specify other requirements
- Symbol ‘Scn’ to specify a setting class number
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oSIST prEN ISO 21920-1:2020
ISO/DIS 21920-1:2020(E)
- Symbol ‘T16%’ or ‘Tmax’ or ‘Tmed’ to specify a tolerance acceptance rule
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 Clause 6.2.
A minimal indication of profile surface texture shall be built up of the graphical symbol, the parameter
designation and the parameter limit value, see Clause 6.3.
In case several parameters are specified the parameter in the first line is relevant for the determination
of default settings (see ISO 21920-3).
NOTE: Exceptions are defined in 9.4.
6.2 Graphical symbol
The design of the graphical symbols contains requirements on the production process.
NOTE 1: Proportions of graphical symbols are defined in Annex A.
NOTE 2: See Figure 4 for layout of the three defined graphical symbols and its interpretation.
NOTE 2: The bar in front of the symbol is for a better distinction of a profile to an areal specification and to
former versions of the standard.

a) any manufacturing process permitted


b) material shall be removed


c) material shall not be removed
Figure 4 — Graphical symbol indicating profile surface texture
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oSIST prEN ISO 21920-1:2020
ISO/DIS 21920-1:2020(E)
6.3 Minimal indication
6.3.1 General
If a minimal indication is specified all defaults shall be applied. Because defaults can not be defined for
all parameter the minimal indication is different for parameter with and without defined defaults.
6.3.2 Minimal indication for parameter with defined defaults
Figure 5 shows all symbols and indications mandatory for a minimal indication of profile surface
texture requirements and parameter with defined defaults.

Key:
a symbol for parameter
b numerical limit value
< > placeholder has to be specified
Figure 5 — Minimal indication for parameter with defined defaults (all defaults apply)
NOTE 1: Parameter with defined defaults are Ra, Rz, Rmax, Rp, Rv and Pt, see ISO 21920-3, Table 3 and 5.
NOTE 2: Exceptions are defined in 9.4.
NOTE 3: See Annex F for examples.
6.3.3 Minimal indication for functional parameter and parameter without defined defaults
Figure 6 shows all symbols and indications mandatory for a minimal indication of profile surface
texture requirements and parameter without defined defaults. All defaults are defined by the
mandatory specified setting class number (Scn) or by the default value of the mandatory profile L-filter
nesting index for R- parameters or profile S-filter nesting index for W- parameter.

Key:
a symbol for parameter
b numerical limit value
c symbol for the specified setting class number Scn or a default value of profile L-filter nesting index for R-
parameters or profile S-filter nesting index for W- parameter
< > placeholder has to be specified
Figure 6 — Minimal indication for parameter without defined defaults
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