National foreword

This British Standard is the UK implementation of EN ISO 21204:2020. It is identical to ISO 21204:2020.

The UK participation in its preparation was entrusted to Technical Committee TPR/1, Technical Product Realization.

A list of organizations represented on this committee can be obtained on request to its secretary.

This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2020.

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).

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.

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 links A, B and C of the chains of standards on form, orientation and location, see Annex D.

The ISO GPS matrix model given in ISO 14638 gives an overview of the ISO GPS system of which this document is a part. The fundamental rules of ISO GPS given in ISO 8015 apply to this document and the default decision rules given in ISO 14253‑1 apply to specifications made in accordance with this document, unless otherwise stated.

In technical drawings, the ideal geometric shape of the workpiece is represented without any deviations and, in general, without consideration of the states of the transitions between adjacent integral features. Nevertheless, for many purposes (the functioning of a part, or out of safety considerations, for example) particular states of transition features need to be indicated. ISO 13715 provides the tools for indicating requirements to edges of undefined shape. These tools are insufficient when the shape of the transition feature is important for functional reasons. Therefore, this document provides a set of tools for indicating transition specifications.

IMPORTANT — Most specification illustrations in this document show edges drawn as sharp corners. They could equally have been drawn showing the nominal geometry of the transition feature, without changing the meaning of the indications. In a computer aided design (CAD) system, the transition feature geometry can be modelled or not without changing the meaning of the indications.

All the specification illustrations in this document show a 90° angle between the two adjacent features. Specifications according to this document have the same meaning, taking the nominal angle into account, regardless of the angle between the two adjacent features.

All figures in this document have been drawn with dimensions and tolerances in millimetres. It should be understood that other units of measurement could have been used equally well without prejudice to the principles established.

This European Standard was approved by CEN on 16 February 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.

European foreword

This document (EN ISO 21204:2020) has been prepared by Technical Committee ISO/TC 213 "Dimensional and geometrical product specifications and verification" in collaboration with Technical Committee CEN/TC 290 “Dimensional and geometrical product specification and verification” the secretariat of which is held by AFNOR.

This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 2020, and conflicting national standards shall be withdrawn at the latest by September 2020.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

Endorsement notice

The text of ISO 21204:2020 has been approved by CEN as EN ISO 21204:2020 without any modification.

1 Scope

This document defines a number of specification operators for the specification of extended edge transition features between features. An edge transition feature is an integral feature connecting two adjacent integral features. The extended edge transition feature includes portions of the adjacent features. All these specifications apply to any line in a defined direction in the extended edge transition feature. This document also defines the specification modifiers and the drawing indications for such transition specifications.

The proportions and dimensions of the graphical symbols to be used are also specified.

The specifications defined in this document are suitable for relatively simple edge transition functions, for example ensuring assembly without interference. For more complex functions, geometrical tolerancing offers more precise tools.

This document is by intention limited to only edge transition features between two planes and between a cylinder and a plane nominally perpendicular to it.

Annex A gives the first approach for an algorithm to identify toleranced features and adjacent reference sections. This algorithm is subject to change as more experience is gathered.

This document provides a set of tools to express several transition specifications. It does not present any information on the relationship between a function or a use and a transition specification.

NOTE 1 Corners (the transition between three or more features) are not edge transition features and are consequently not covered by this document.

NOTE 2 An edge transition feature exists between two single features. A defined edge transition feature has a defined nominal shape and is not sharp (r = 0).

2 Normative references

3 Terms and definitions

4 Basic concepts

5 General indication rules

5.1 Symbols

5.2 Indications using the transition specification symbol

5.3 Indication areas around the transition specification symbol

6 Circular edge transition feature indications

6.1 Fixed radius profile specification

6.2 Variable radius profile specification

6.3 Consistent radius profile specification

6.4 Maximum material radius boundary specification

6.5 Least material radius boundary specification

6.6 Maximum material radius boundary with profile specification

6.7 Least material radius boundary with profile specification

6.8 Combined maximum material and least material radius boundary specification

7 Chamfer edge transition feature indications

7.1 Fixed chamfer profile specification

7.2 Variable chamfer profile specification

7.3 Consistent chamfer profile specification

7.4 Maximum material chamfer boundary specification

7.5 Least material chamfer boundary specification

7.6 Maximum material chamfer boundary with profile specification

7.7 Least material chamfer boundary with profile specification

7.8 Combined maximum material and least material chamfer boundary specification

8 Elliptical edge transition feature indications

8.1 Fixed elliptical profile specification

8.2 Variable elliptical profile specification

8.3 Consistent elliptical profile specification

8.4 Maximum material elliptical boundary specification

8.5 Least material elliptical boundary specification

8.6 Maximum material elliptical boundary with profile specification

8.7 Least material elliptical boundary with profile specification

8.8 Combined maximum material and least material elliptical boundary specification

9 Edge transition feature defined by CAD

9.1 CAD profile specification

9.2 Maximum material CAD profile boundary specification

9.3 Least material CAD profile boundary specification

9.4 Maximum material CAD profile boundary with profile specification

9.5 Least material CAD profile boundary with profile specification

10 Rules for supplemental indications

10.1 Symbols

10.2 Limits of different nominal shapes

10.3 Extent of the toleranced feature

10.4 Tolerance zone offset

10.5 Indication of primary adjacent reference section

10.6 Indication of several toleranced features

10.7 Indications using the between symbol

10.8 Around a feature indications

10.9 General transition specifications

Bibliography

BS EN ISO 21204:2020

Geometrical product specifications (GPS). Transition specification

Current

Published:

31 Mar 2020