oSIST prEN ISO 5459:2018

Geometrical product specifications (GPS) - Geometrical tolerancing - Datums and datum systems (ISO/DIS 5459.2:2017)

2017-09-20: 2nd enquiry decided to follow ISO

Geometrische Produktspezifikation (GPS) - Geometrische Tolerierung - Bezüge und Bezugssysteme (ISO/DIS 5459.2:2017)

Spécification géométrique des produits (GPS) - Tolérancement géométrique - Références spécifiées et systèmes de références spécifiées (ISO/DIS 5459.2:2017)

Specifikacija geometrijskih veličin izdelka (GPS) - Geometrijsko toleriranje - Reference in sistemi referenc (ISO/DIS 5459.2:2017)

General Information

• Status: Not Published
• Public Enquiry End Date: 14-Jan-2018
• ICS: 17.040.10 - Limits and fits
• ICS: 17.040.40 - Geometrical Product Specification (GPS)
• Technical Committee: ISEL - Mechanical elements
• Current Stage: 98 - Abandoned project (Adopted Project)
• Start Date: 14-Jan-2020
• Due Date: 19-Jan-2020
• Completion Date: 14-Jan-2020
• Ref Project: prEN ISO 5459 - Geometrical product specifications (GPS) - Geometrical tolerancing - Datums and datum systems (ISO/DIS 5459.2:2017)

RELATIONS

• Revised: SIST EN ISO 5459:2011 - Geometrical product specifications (GPS) - Geometrical tolerancing - Datums and datum systems (ISO 5459:2011)
• Effective Date: 01-Jun-2016

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN ISO 5459:2018
01-januar-2018
6SHFLILNDFLMDJHRPHWULMVNLKYHOLþLQL]GHOND*36*HRPHWULMVNRWROHULUDQMH
5HIHUHQFHLQVLVWHPLUHIHUHQF,62',6

Geometrical product specifications (GPS) - Geometrical tolerancing - Datums and datum

systems (ISO/DIS 5459.2:2017)
Geometrische Produktspezifikation (GPS) - Geometrische Tolerierung - Bezüge und
Bezugssysteme (ISO/DIS 5459.2:2017)
Spécification géométrique des produits (GPS) - Tolérancement géométrique -
Références spécifiées et systèmes de références spécifiées (ISO/DIS 5459.2:2017)
Ta slovenski standard je istoveten z: prEN ISO 5459
ICS:
17.040.10 Tolerance in ujemi Limits and fits
17.040.40 6SHFLILNDFLMDJHRPHWULMVNLK Geometrical Product
YHOLþLQL]GHOND*36 Specification (GPS)
oSIST prEN ISO 5459:2018 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN ISO 5459:2018
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oSIST prEN ISO 5459:2018
DRAFT INTERNATIONAL STANDARD
ISO/DIS 5459.2
ISO/TC 213 Secretariat: BSI
Voting begins on: Voting terminates on:
2017-11-20 2018-01-15
Geometrical product specifications (GPS) — Geometrical
tolerancing — Datums and datum systems

Spécification géométrique des produits (GPS) — Tolérancement géométrique — Références spécifiées et

systèmes de références spécifiées
ICS: 17.040.10; 01.100.20
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 5459.2:2017(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 2017
---------------------- Page: 3 ----------------------
oSIST prEN ISO 5459:2018
ISO/DIS 5459.2:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© 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

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2017 – All rights reserved
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oSIST prEN ISO 5459:2018
ISO/DIS 5459.2:2017(E)
Contents Page

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

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

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

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

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

4 Symbols ............................................................................................................................................................... 7

5 Datum system basics ................................................................................................................................... 10

5.1 Role of datum system .................................................................................................................................. 10

5.2 Concepts .......................................................................................................................................................... 10

5.2.1 Introduction ................................................................................................................................................... 10

5.2.2 Associated feature in link with a datum system ............................................................................... 10

5.2.3 Situation features of associated feature .............................................................................................. 11

5.2.4 Datum used to constrain orientation or location of other ideal features ................................ 12

5.2.5 Operations and types of features in the process to establish a datum ..................................... 12

5.2.6 Consideration for indication of datum system .................................................................................. 14

6 Datum feature indication .......................................................................................................................... 14

6.1 Datum feature indicator ............................................................................................................................ 14

6.2 Datum feature identifier ............................................................................................................................ 15

6.3 Identification of a single feature as datum feature .......................................................................... 15

6.4 Completeness of datum feature .............................................................................................................. 17

6.4.1 Generality ........................................................................................................................................................ 17

6.4.2 Datum features established from a complete feature .................................................................... 18

6.4.3 Datum features established from a non‐complete feature defined by one or more

datum targets................................................................................................................................................. 18

6.4.4 Datum feature defined as one located restricted feature .............................................................. 25

6.4.5 Datum feature defined as one unlocated restricted feature ........................................................ 26

7 Specification of datums and datum systems ...................................................................................... 26

7.1 General ............................................................................................................................................................. 26

7.2 Interdependency to define a partial toleranced feature and partial datum feature ........... 28

7.3 Datum system indication – Datum section .......................................................................................... 29

7.4 Indication of a datum in a datum indicator of a datum section – Datum indicator .............. 30

7.5 Rules to define associated features from datum features ............................................................. 31

7.5.1 General ............................................................................................................................................................. 31

7.5.2 Rule a — Associated feature type ........................................................................................................... 32

7.5.3 Rule b — Dimension of an associated feature ................................................................................... 34

7.5.4 Rule c — Material constraints for associated feature ..................................................................... 35

7.5.5 Rule d — Constraint between associated features in a common datum .................................. 36

7.5.6 Rule e — Constraint between associated features in a datum system ...................................... 36

7.6 Locked or released degrees of freedom for the members of its datum system ..................... 42

7.7 Special indications for common datum ................................................................................................ 45

7.8 Identifications of situation feature on technical product documentation .............................. 46

7.9 Degrees of freedom indication in relation with a datum system ................................................ 47

7.10 Establishment of a coordinate system from a datum system ....................................................... 48

ii © ISO 2017 – All rights reserved
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oSIST prEN ISO 5459:2018
ISO/DIS 5459.2:2017(E)

7.11 Application of Ⓜ, Ⓛ and Ⓟ modifiers in a datum indicator ......................................................... 49

8 Specification operator for datum ............................................................................................................ 51

8.1 Introduction.................................................................................................................................................... 51

8.2 ISO default specification operator for datum ..................................................................................... 51

8.2.1 For association ............................................................................................................................................... 51

8.2.2 For filtration ................................................................................................................................................... 52

8.3 Special specification operator for datum ............................................................................................. 53

8.3.1 General ............................................................................................................................................................. 53

8.3.2 Filtration specification elements for datum ....................................................................................... 54

8.3.3 Association specification elements for datum ................................................................................... 55

8.4 Drawing‐specific default for datum ....................................................................................................... 57

Annex A (informative) Association for datums ............................................................................................... 58

Annex B (informative) Invariance classes ........................................................................................................ 65

Annex C (informative) Indication and meaning of datum systems for some examples ................... 67

Annex D (normative) Datum feature indicator for threads ....................................................................... 93

Annex E (informative) Examples of a datum system or a common datum established with

contacting features....................................................................................................................................... 95

Annex F (informative) Examples of a datum system established from datum targets .................. 100

Annex G (informative) Filter symbols and attached nesting index ...................................................... 105

Annex H (normative) Relations and dimensions of graphical symbols .............................................. 106

Annex I (informative) Former practice ........................................................................................................... 107

Annex J (informative) Relationship to the GPS matrix model ................................................................ 108

Bibliography .............................................................................................................................................................. 110

© ISO 2017 – All rights reserved iii
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oSIST prEN ISO 5459:2018
ISO/DIS 5459.2:2017(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: www.iso.org/iso/foreword.html.

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

specifications and verification.

This third edition cancels and replaces the second edition (ISO 5459:2011), which has been technically

revised with the following main changes:

 the default association criteria has been changed by defining only one independently to the shape

of the nominal integral feature;

 the representation and indication to identify the plane, the straight line and the point of a datum

system, have been introduced;
 the default filtration method is now defined;
 it is allowed to change default filtration and association methods;
 it is allowed to define a coordinate system from a datum system.
iv © ISO 2017 – All rights reserved
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oSIST prEN ISO 5459:2018
ISO/DIS 5459.2:2017(E)
Introduction

ISO 5459 is a geometrical product specification (GPS) standard and is to be regarded as a general GPS

standard (see ISO 14638). It influences the chain links A, B and C of the chain of standards on size,

orientation, location, run‐out, profile surface texture and areal 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 specifications made in accordance with this

standard unless otherwise indicated.

For more detailed information of the relation of this document to the GPS matrix model, see Annex I.

For the definitive presentation (proportions and dimensions) of symbols for geometrical tolerancing,

see ISO 7083.

This document provides tools to express location or orientation constraints, or both, for a tolerance

zone. It does not provide information about the relationship between datums or datum systems and

functional requirements or applications.
Former practice of datums is given in Annex H.
© ISO 2017 – All rights reserved v
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oSIST prEN ISO 5459:2018
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oSIST prEN ISO 5459:2018
DRAFT INTERNATIONAL STANDARD ISO/DIS 5459:2017(E)
Geometrical product specification (GPS) — Geometrical
tolerances — Datum and datum systems
1 Scope

This document specifies terminology, rules and methodology for the indication and understanding of

datums and datum systems in technical product documentation. This document also provides

explanations to assist the user in understanding the concepts involved.

This document defines the specification operator (see ISO 17450‐2) used to establish a datum or a

datum system. The verification operator (see ISO 17450‐2) can take different forms (physically or

mathematically) and is not the subject of this document.

NOTE The detailed rules for maximum and least material requirements for datums are given in ISO 2692.

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 128‐24, Technical drawings — General principles of presentation — Part 24: Lines on mechanical

engineering drawings

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

orientation, location and run‐out

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

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

ISO 17450‐1, Geometrical product specifications (GPS) — General concepts — Part 1: Model for

geometrical specification and verification

ISO 17450‐2, Geometrical product specifications (GPS) — General concepts — Part 2: Basic tenets,

specifications, operators, uncertainties and ambiguities
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 1101, ISO 2692, ISO 17450‐1,

ISO 17450‐2 and the following 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/
© ISO 2017 – All rights reserved 1
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oSIST prEN ISO 5459:2018
ISO/DIS 5459.2:2017(E)
3.1
datum feature
real (non‐ideal) integral feature used for establishing a single datum

Note 1 to entry: A datum feature can be a complete surface, a set of one or more portions of a complete surface, or

a feature of size.

Note 2 to entry: An illustration showing the relations between datum feature, associated feature and datum is

given in Figure 2.
3.2
datum target

specific portion, which is nominally a point, a line segment or an area, taken from a datum feature and

which is totally located on the real workpiece

Note 1 to entry: Where the datum target is a point, a line or an area, it is indicated as a datum target point, a datum

target line or a datum target area, respectively.
3.3
moveable datum target

specific portion, which is nominally a point, a line segment or an area, taken from a datum feature and

which has one freedom of translation along a defined path from other datums established on the real

workpiece
3.4
associated feature (used for datum)

ideal feature which is fitted to the datum feature with a specific association criterion

Note 1 to entry: The type of the associated feature is by default the same as the type of the nominal integral

feature used to establish the datum (for an exception see 7.5.2).

Note 2 to entry: The associated feature for establishing a datum simulates by default the contact between the real

surface of the workpiece and other components.

Note 3 to entry: An illustration showing the relations between datum feature, associated feature and datum is

given in Figure 2.

Note 4 to entry: An associated feature may have the same shape as the nominal integral datum feature or it may be

another shape defined as a contacting feature (see 3.22 and Figure 1).
3.5
datum

set of one or more situation features (point, line, plane) issued from one or more associated integral

features

Note 1 to entry: A datum can be used to locate or orientate an ideal feature (e.g. a tolerance zone, an intersection

plane, an orientation plane, a reference feature or an ideal feature representing for instance a virtual condition).

Note 2 to entry: Datums with maximum material condition or least material condition (see ISO 2692) are not

covered in this document.

Note 3 to entry: When a datum is established, for example, on a complex surface, the datum consists of a plane, a

straight line or a point, or a combination thereof. The modifier [SL], [PL] or [PT], or a combination thereof, can be

attached to the datum identifier to limit the situation feature(s) taken into account relative to the surface.

Note 4 to entry: An illustration showing the relation between datum feature, associated feature and datum is given

in Figure 2.
2 ©ISO2017 – All rights reserved
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oSIST prEN ISO 5459:2018
ISO/DIS 5459.2:2017(E)
Note 5 to entry: Without qualifier, a datum is a single datum or a common datum.
3.6
single datum

datum established from one datum feature taken from one single surface or from one feature of size

Note 1 to entry: The invariance class of a single surface can be complex, prismatic, helical, cylindrical, revolute,

planar or spherical. A set of situation features defining the datum (see Table B.1) corresponds to each type of

single surface.
Note 2 to entry: See the rule in 7.4.
3.7
common datum

datum established from two or more datum features after simultaneous associations without specific

order and with interrelated constraints

Note 1 to entry: To define a common datum, it is necessary to consider the collected surface created by the

identified datum features. The invariance class of a collected surface can be complex, prismatic, helical, cylindrical,

revolute, planar or spherical (see Table B.1).
Note 2 to entry: See the rule in 7.4.

Note 3 to entry: The result of the common datum cannot be considered as a collection of the situation features of

each associated feature. For example a common datum, established from two parallel non‐coaxial cylinders, is a

set of a plane and a straight line contained in the plane. See Examples 1 to 4 in 7.5.6.

3.8
datum system

set of one or more situation features (point, straight line, plane) resulting from one or more datums

established in a specific order from one or more datum features

Note 1 to entry: To define a datum system, it is necessary to consider the collected surface created by the

identified datum features to identify its invariance class (see Table B.1).

Note 2 to entry: A datum system can consist of one common datum or one single datum.

Note 3 to entry: The role of a datum system is described in 5.1.
3.9
datum section
specification element containing one, two or three datum indicators

Note 1 to entry: A datum section can be used as a part of a tolerance indicator, an intersection plane indicator, an

orientation plane indicator, collection plane indicator or a direction feature indicator (see ISO 1101). See Figure 2.

3.10
datum indicator
specification element containing only one datum identifier
Note 1 to entry: See Figure 2.
3.11
datum identifier

label, designating a datum in a datum indicator, which is identical to the datum feature identifier in the

case of a single datum, or which is a sequence of datum feature identifiers separated by an hyphen in

the case of a common datum
© ISO 2017 – All rights reserved 3
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oSIST prEN ISO 5459:2018
ISO/DIS 5459.2:2017(E)
Note 1 to entry: See Figure 2.
3.12
situation feature identifier

label, designating a situation feature (point, straight line or plane) related to a datum

3.13
datum feature identifier

label, defined by one or more capital letters, identifying the nominal integral feature, corresponding to a

datum feature
Note 1 to entry: The same label is also used to identify a single datum.
Note 2 to entry: see Table 1 and Clause 6.
3.14
datum feature indicator

graphical symbol used to define an integral feature as a datum feature and containing a datum feature

identifier
Note 1 to entry: See Table 1 and 5.2.
3.15
primary datum
datum indicated in the first datum indicator of the datum section

Note 1 to entry: A primary datum is not influenced by constraints from other datums (see 7.1).

3.16
secondary datum
datum indicated in the second datum indicator of the datum section

Note 1 to entry: A secondary datum is constrained at least in orientation from the primary datum (see 7.1).

3.17
tertiary datum
datum indicated in the third datum indicator of the datum section

Note 1 to entry: The tertiary datum is constrained at least in orientation from the primary datum and the

secondary datum (see 7.1).
3.18
collected surface
two or more surfaces considered simultaneously as a surface

Note 1 to entry: Table B.1 is used to determine the invariance class of datums or datum systems when using a

collection of surfaces.

Note 2 to entry: Two intersecting planes may be considered simultaneously or sequentially (one after the other).

When the two intersecting planes are considered simultaneously as a single surface, that surface is a collected

surface.
3.19
objective function
objective function for association
formula that describes the goal of association

Note 1 to entry: In this document, the term "objective function" refers to "objective function for association".

4 ©ISO2017 – All rights reserved
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oSIST prEN ISO 5459:2018
ISO/DIS 5459.2:2017(E)

Note 2 to entry: The objective functions are usually named and mathematically described: maximum inscribed,

minimum zone, etc.
3.20
(association) constraint
requirement to establish an associated feature

EXAMPLE Orientation constraint, location constraint, material constraint or intrinsic characteristic

constraint.
3.20.1
orientation constraint

constraint on one or more rotational degrees of freedom between the situation features of associated

feature
3.20.2
location constraint

constraint on one or more translational degrees of freedom between the situation features of associated

feature
3.20.3
material constraint

additional condition to the location of the associated feature, relative to the material of the feature,

while optimizing an objective function

Note 1 to entry: For example, an association constraint can be that all distances between the associated feature

and the datum feature are positive or equal to zero, i.e. the associated feature is outside the material.

3.20.4
intrinsic characteristic constraint

additional requirement applied to the intrinsic characteristic of an associated feature whether it is

considered as fixed or variable
3.21
association criterion
objective function with or without constraints, defined for an association
Note 1 to entry: Several constraints may be defined for an association.

Note 2 to entry: Association results (associated features) may differ, depending upon the choice of association

criterion.
Note 3 to entry: Default association criteria are defined in 8.2.
3.22
contacting feature

ideal feature, with theoretical exact geometry (shape and dimension), different from the nominal

geometry of the integral geometrical feature with which it is in contact

Note 1 to entry: A contacting feature can be used to define a set of one or more datum features, and/or to establish

a datum.
Note 2 to entry: See rule a in 7.5.2.
Note 3 to entry: See Figure 1.
© ISO 2017 – All rights reserved 5
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oSIST prEN ISO 5459:2018
ISO/DIS 5459.2:2017(E)
a) Contacting feature on nominal model b) Contacting feature on real workpiece
Key

1 contacting feature: ideal sphere in contact with the datum feature or the feature under consideration

2 features under consideration: nominal trapezoidal slot (collection of two non‐parallel surfaces)

3 datum feature: real feature corresponding to the trapezoidal slot (collection of two non‐parallel surfaces)

Figure 1 — Example of a contacting feature
3.23
datum coordinate system
cartesian coordinate system established from a datum system

Note 1 to entry: The datum coordinate system can describe some degrees of freedoms, which are locked through

the datum system.
Note 2 to entry: Using a datum coordinate system is optional.

EXAMPLE A datum system defined by only a primary datum, which is a plane, can allow establishing a

non‐unique datum coordinate system, one translation and two rotations be
...

SLOVENSKI STANDARD
oSIST prEN ISO 5459:2016
01-junij-2016

6SHFLILNDFLMDJHRPHWULMVNLKYHOLþLQL]GHOND*HRPHWULMVNRWROHULUDQMH5HIHUHQFHLQ

VLVWHPLUHIHUHQF,62',6

Geometrical product specifications (GPS) - Geometrical tolerancing - Datums and datum

systems (ISO/DIS 5459:2016)
Geometrische Produktspezifikation (GPS) - Geometrische Tolerierung - Bezüge und
Bezugssysteme (ISO/DIS 5459:2016)
Spécification géométrique des produits (GPS) - Tolérancement géométrique -
Références spécifiées et systèmes de références spécifiées (ISO/DIS 5459:2016)
Ta slovenski standard je istoveten z: prEN ISO 5459
ICS:
17.040.10 Tolerance in ujemi Limits and fits
17.040.40 6SHFLILNDFLMDJHRPHWULMVNLK Geometrical Product
YHOLþLQL]GHOND*36 Specification (GPS)
oSIST prEN ISO 5459:2016 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN ISO 5459:2016
---------------------- Page: 2 ----------------------
oSIST prEN ISO 5459:2016
DRAFT INTERNATIONAL STANDARD
ISO/DIS 5459
ISO/TC 213 Secretariat: DS
Voting begins on: Voting terminates on:
2016-03-24 2016-06-23
Geometrical product specifications (GPS) — Geometrical
tolerancing — Datums and datum systems

Spécification géométrique des produits (GPS) — Tolérancement géométrique — Références spécifiées et

systèmes de références spécifiées
ICS: 17.040.10; 01.100.20
ISO/CEN PARALLEL PROCESSING
This draft has been developed within the International Organization for
Standardization (ISO), and processed under the ISO lead mode of collaboration
as defined in the Vienna Agreement.
This draft is hereby submitted to the ISO member bodies and to the CEN member
bodies for a parallel three month enquiry.
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
To expedite distribution, this document is circulated as received from the
IN ADDITION TO THEIR EVALUATION AS
committee secretariat. ISO Central Secretariat work of editing and text
BEING ACCEPTABLE FOR INDUSTRIAL,
composition will be undertaken at publication stage.
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 5459:2016(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 2016
---------------------- Page: 3 ----------------------
oSIST prEN ISO 5459:2016
ISO/DIS 5459:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland

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

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
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Contents Page

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

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

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

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

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

4 Symbols .............................................................................................................................. 7

5 Role of a datum system ........................................................................................................ 8

6 General concepts................................................................................................................. 9

7 Graphical language ............................................................................................................ 12

7.1 General ............................................................................................................................. 12

7.2 Indication of datum features ............................................................................................... 12

7.2.1 Datum feature indicator ...................................................................................................... 12

7.2.2 Datum feature identifier ...................................................................................................... 13

7.2.3 Datum targets .................................................................................................................... 13

7.2.4 Contacting features............................................................................................................ 16

7.3 Specification of datums and datum systems........................................................................ 17

7.4 Indication and meaning of rules .......................................................................................... 17

7.4.1 General ............................................................................................................................. 17

7.4.2 Rules (potential new clause 8) ............................................................................................ 18

7.5 Datum section (potential new clause 9) ............................................................................... 43

7.5.1 General ............................................................................................................................. 43

7.5.2 ISO default specification operator for single or common datum ............................................ 43

7.5.3 Individual specification operator for single or common datum.............................................. 43

7.5.4 Datum filtration specification elements ............................................................................... 44

7.5.5 Datum association specification elements........................................................................... 45

7.5.6 Drawing-specific default for datum ..................................................................................... 46

Annex A (normative) Association for datums ................................................................................. 47

A.1 Basic concepts .................................................................................................................. 47

A.2 Association methods ......................................................................................................... 48

A.2.1 General ............................................................................................................................. 48

A.2.2 Association for single datums ............................................................................................ 50

A.2.3 Association for common datums ........................................................................................ 51

A.2.4 Association for datum systems........................................................................................... 53

Annex B (informative) Invariance classes ...................................................................................... 54

Annex C (informative) Indication and meaning of datum systems for some examples ...................... 56

C.1 Examples of datum systems constituted by one single datum .............................................. 56

C.1.1 Plane................................................................................................................................. 56

C.1.2 Cylinder ............................................................................................................................ 57

C.1.3 Cone ................................................................................................................................. 58

C.1.4 Sphere .............................................................................................................................. 59

C.1.5 Particular situation feature ................................................................................................. 60

C.1.6 Obvious situation feature ................................................................................................... 61

C.1.7 Only one situation feature needed....................................................................................... 62

C.1.8 Complex surface................................................................................................................ 63

C.1.9 Intersecting planes ............................................................................................................ 64

C.1.10 Two parallel opposite planes (defined as a feature of size) ................................................... 65

C.1.11 Three datum targets on a plane........................................................................................... 66

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C.2 Examples of datum systems constituted by one common datum .......................................... 67

C.2.1 Two coplanar planes .......................................................................................................... 67

C.2.2 Two coaxial cylinders ......................................................................................................... 68

C.2.3 Plane and cylinder perpendicular to each other ................................................................... 69

C.2.4 Two parallel cylinders ........................................................................................................ 70

C.2.5 Pattern of five cylinders...................................................................................................... 71

C.2.6 Two parallel planes ............................................................................................................ 72

C.3 Examples of datum systems constituted by more than one single datum .............................. 73

C.3.1 Three perpendicular planes ................................................................................................ 73

C.3.2 Perpendicular plane and cylinder ........................................................................................ 75

Annex D (normative) Associated feature established from a thread or a gear ................................... 77

D.1 General ............................................................................................................................. 77

D.2 Indication for a thread ........................................................................................................ 78

D.3 Indication for a gear ........................................................................................................... 79

Annex E (informative) Examples of a datum system or a common datum established with

contacting features ............................................................................................................ 83

E.1 Example 1.......................................................................................................................... 83

E.2 Example 2.......................................................................................................................... 84

E.3 Example 3.......................................................................................................................... 85

E.4 Example 4.......................................................................................................................... 86

E.5 Example 5 — Example for a “three jaw chuck” ..................................................................... 87

Annex F (informative) Filter symbols and attached nesting index .................................................... 88

Annex G (informative) Some basic examples of datum ................................................................... 89

G.1 General ............................................................................................................................. 89

G.2 Associated plane used to establish a datum ........................................................................ 89

G.3 Associated circle and cylinder used to establish a datum ..................................................... 91

Annex H (normative) Relations and dimensions of graphical symbols ............................................. 95

Annex I (informative) Former practice ............................................................................................ 96

Annex J (informative) Relationship to the GPS matrix model ........................................................... 97

J.1 General ............................................................................................................................. 97

J.2 Information about this International Standard and its use ..................................................... 97

J.3 Position in the GPS matrix model ........................................................................................ 97

J.4 Related International Standards .......................................................................................... 97

Bibliography ................................................................................................................................. 98

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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 2.

The main task of technical committees is to prepare International Standards. 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.

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.

ISO 5459 was prepared by Technical Committee ISO/TC 213, Dimensional and geometrical product

specifications and verification.

This third edition cancels and replaces the second edition (ISO 5459:2011), which has been technically

revised.
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Introduction

ISO 5459 is a geometrical product specification (GPS) standard and is to be regarded as a general GPS

standard (see ISO 14638). It influences the chain links A, B and C of the chain of standards on size,

orientation, location, run-out, profile surface texture and areal surface texture.

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

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

decision rules given in ISO 14253-1 apply to specifications made in accordance with this standard unless

otherwise indicated.

For more detailed information of the relation of this International Standard to the GPS matrix model, see

Annex J.

For the definitive presentation (proportions and dimensions) of symbols for geometrical tolerancing, see

ISO 7083.

This International Standard provides tools to express location or orientation constraints, or both, for a

tolerance zone. It does not provide information about the relationship between datums or datum systems and

functional requirements or applications.
Former practice of datums is given in Annex I.
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WORKING DRAFT ISO/DIS 5459:2016(E)
Geometrical product specification (GPS) — Geometrical
tolerances — Datum and datum systems
1 Scope

This International Standard specifies terminology, rules and methodology for the indication and understanding

of datums and datum systems in technical product documentation. This International Standard also provides

explanations to assist the user in understanding the concepts involved.

This International Standard defines the specification operator (see ISO 17450-2) used to establish a datum or

datum system. The verification operator (see ISO 17450-2) can take different forms (physically or

mathematically) and is not the subject of this International Standard.

NOTE The detailed rules for maximum and least material requirements for datums are given in ISO 2692.

2 Normative references

The following referenced documents are indispensable for the application 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 128-24:2014, Technical drawings — General principles of presentation — Part 24: Lines on mechanical

engineering drawings

ISO/FDIS 1101:2015 , Geometrical product specifications (GPS) — Geometrical tolerancing — Tolerances of

form, orientation, location and run-out

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

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

ISO 17450-1, Geometrical product specifications (GPS) — General concepts — Part 1: Model for geometrical

specification and verification

ISO 17450-2, Geometrical product specifications (GPS) — General concepts — Part 2: Basic tenets,

specifications, operators, uncertainties and ambiguities
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO/FDIS 1101:2015 , ISO 2692,

ISO 17450-1, ISO 17450-2 and the following apply.
3.1
situation feature

point, straight line, plane or helix from which the location and/or orientation of a geometrical feature, can be

defined
1) Under finalisation.
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3.2
datum feature
real (non-ideal) integral feature used for establishing a single datum

Note 1 to entry: A datum feature can be a complete surface, a set of one or more portions of a complete surface, or a

feature of size.

Note 2 to entry: An illustration showing the relations between datum feature, associated feature and datum is given in

Figure 2.
3.3
datum target

specific portion, which is nominally a point, a line segment or an area, taken of complete real (non-ideal)

integral feature used for establishing a datum

Note 1 to entry: Where the datum target is a point, a line or an area, it is indicated as a datum target point, a datum target

line or a datum target area, respectively.
3.4
moveable datum target
datum target moving along a defined path
3.5
associated feature

ideal feature which is fitted to the datum feature with a specific association criterion

Note 1 to entry: The type of the associated feature is by default the same as the type of the nominal integral feature used

to establish the datum (for an exception see 7.4.2.6.2).

Note 2 to entry: The associated feature for establishing a datum simulates the contact betw een the real surface of the

w orkpiece and other components.

Note 3 to entry: An illustration showing the relations between datum feature, associated feature and datum is given in

Figure 2.

Note 4 to entry: An associated feature may have the same shape as the nominal integral datum feature or it may be

another shape defined as a contacting feature.
Note 5 to entry: See Figure 1.
3.6
datum

one or more situation features (point, line, plane, helix) derived from one or more associated integral features

Note 1 to entry: a datum can be used to locate or orientate an ideal feature (eg. a tolerance zone, an intersection plane,

an orientation plane, a reference feature, or an ideal feature representing for instance a virtual condition)

Note 2 to entry: A datum is a theoretically exact reference; it is defined by a plane, a straight line or a point, or a

combination thereof, i.e one of the follow ing possibilities:
 [plane; straight line; point] or
 [plane; straight line] or
 [straight line; point] or
 [plane] or
 [point] or
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 [straight line] or
 [helix].

Note 3 to entry: The concept of datums is inherently reliant upon the invariance class concept (see Annex A and Annex B).

Note 4 to entry: Datums w ith maximum material condition or least material condition (see ISO 2692) are not covered in

this International Standard .

Note 5 to entry: When a datum is established, for example, on a complex surface, the datum consists of a plane, a straight

line or a point, or a combination thereof. The modifier [SL], [PL] or [PT], or a combination thereof, can be attached to the

datum identifier to limit the situation feature(s) taken into account relative to the surface.

Note 6 to entry: An illustration showing the relation between datum feature, associated feature and datum is given in

Figure 2.
3.7
single datum

datum established from one datum feature taken from one single surface or from one feature of size

Note 1 to entry: The invariance class of a single surface can be complex, prismatic, helical, cylindrical, revolute, planar or

spherical. A set of situation features defining the datum (see Table B.1) corresponds to each type of single surface.

Note 2 to entry: See rule 5 in 7.4.2.5.
3.8
common datum

datum established simultaneously (considering the collection of associated feature together with constraint

between them), without specific order, from two or more datum features

Note 1 to entry: To define a common datum, it is necessary to consider the collection surface created by the considered

datum features. The invariance class of a collection surface can be complex, prismatic, helical, cylindrical, revolute, planar

or spherical (see Table B.1).
Note 2 to entry: See rule 5 in 7.4.2.5.
3.9
datum system

set of one or more datums established in a specific ordered sequence from one or more datum features

Note 1 to entry: To define a datum system, it is necessary to consider the collection surface created by the considered

datum features to identify its invariance class (see Table B.1).

Note 2 to entry: A datum system can consist only in a common datum or a single datum.

Note 3 to entry: the role of datum system is described in Clause 5
3.10
datum section
specification element containing one, two or three datum indicators

Note 1 to entry: A datum section can be used as a part of a tolerance indicator, an intersection plane indicator, an

orientation plane indicator, collection plane indicator or a direction feature indicator (see ISO/FDIS 1101:2015 ).

3.11
datum indicator
specification element containing only one single datum or common datum
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3.12
primary datum

single datum or common datum, which is indicated in the first datum indicator of the datum section and that is

not influenced by constraints from other datums

Note 1 to entry: The primary datum is indicated in the first datum indicator of the datum section (see 7.3).

3.13
secondary datum

single datum or common datum which is indicated in the second datum indicator of the datum section and that

is constrained at least in orientation from the primary datum

Note 1 to entry: The secondary datum is indicated in the second datum indicator of the datum section (see 7.3).

3.14
tertiary datum

single datum or common datum which is indicated in the third datum indicator of the datum section and that is

constrained at least in orientation from the primary datum and the secondary datum

Note 1 to entry: The tertiary datum is indicated in the third datum indicator of the datum section (see 7.3).

3.15
collection surface
two or more surfaces considered simultaneously as a surface

Note 1 to entry: Table B.1 is used to determine the invariance class of a datum or datum systems w hen using a collection

of surfaces.

Note 2 to entry: Tw o intersecting planes may be considered simultaneously or sequentially (one after the other). When the

tw o intersecting planes are considered simultaneously as a single surface, that surface is a collection surface.

3.16
objective function
objective function for association
formula that describes the quality of association

Note 1 to entry: In this International Standard, the term “objective function” refers to “objective function for association”.

Note 2 to entry: The objective functions are usually named and mathematically described: maximum inscribed, minimum

zone, etc.
3.17
association

operation used to fit ideal feature(s) to non-ideal feature(s) according to an association criterion

[ISO 17450-1:2011, 3.4.1.4]
3.18
(association) constraint
requirement on the associated feature
Note 1 to entry:

EXAMPLE Orientation constraint, location constraint, material constraint or intrinsic characteristic constraint.

3.18.1
orientation constraint

requirement on one or more rotational degrees of freedom used to establish the associated feature

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3.18.2
location constraint

requirement on one or more translational degrees of freedom used to establish the associated feature

3.18.3
material constraint

additional condition to the location of the associated feature, relative to the material of the feature, while

optimizing an objective function

Note 1 to entry: For example, an association constraint can be that all distances betw een the associated feature and the

datum feature are positive or equal to zero, i.e. the associated feature is outside the material.

3.18.4
intrinsic characteristic constraint

additional requirement applied to the intrinsic characteristic of an associated feature whether it is considered

fixed or variable
3.19
association criterion
objective function with or without constraints, defined for an association
Note 1 to entry: Several constraints may be defined for an association.

Note 2 to entry: Association results (associated features) may differ, depending upon the choice of association criterion.

Note 3 to entry: Default association criteria are defined in Annex A.
3.20
contacting feature

ideal feature, which can have a nominal shape different from the shape of the integral geometrical feature,

with which it is in contact

Note 1 to entry: A contacting feature can be used to define a set of one or more datum features, and/or to establish a

datum.
Note 2 to entry: See rule 6.a in 7.4.2.6.2.
Note 3 to entry: See Figure 1.
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a) Contacting feature on nominal model b) Contacting feature on real workpiece

Key

1 contacting feature: ideal sphere in contact w ith the datum feature or the feature under consideration

2 features under consideration: nominal trapezoidal slot (collection of two non-parallel surfaces)

3 datum feature: real feature corresponding to the trapezoidal slot (collection of tw o non-parallel surfaces)

Figure 1 — Example of a contacting feature
3.21
invariance class

group of ideal features for which the nominal surface is invariant for the same degrees of freedom

Note 1 to entry: There are seven invariance classes (see Annex B).
3.22
theoretically exact dimension
TED

linear or angular dimension used in GPS operations to define theoretically exact geometry, extents, locations

and orientations of features
Note 1 to entry: For the purpose of this International Standar
...