ISO 2903:2016

ISO metric trapezoidal screw threads — Tolerances

ISO 2903:2016 specifies a tolerance system for metric trapezoidal screw threads in accordance with ISO 2902. The tolerances refer to the design profile in accordance with ISO 2901. The tolerance system does not apply to trapezoidal screw threads with special requirements on axial displacement, for example, machine tool lead and feed screws and nuts.

Filetages métriques trapézoïdaux ISO — Tolérances

General Information

• Status: Published
• Publication Date: 11-Aug-2016
• ICS: 21.040.10 - Metric screw threads
• Technical Committee: ISO/TC 1 - Screw threads
• Drafting Committee: ISO/TC 1 - Screw threads

Relations

• Revises: ISO 2903:1993 - ISO metric trapezoidal screw threads — Tolerances
• Effective Date: 04-Nov-2015

Standards Content (Sample)

DRAFT INTERNATIONAL STANDARD
ISO/DIS 2903
ISO/TC 1 Secretariat: SAC
Voting begins on: Voting terminates on:
2016-01-13 2016-04-13
ISO metric trapezoidal screw threads — Tolerances
Filetages métriques trapézoïdaux ISO — Tolérances
ICS: 21.040.10
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.
IN ADDITION TO THEIR EVALUATION AS
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 2903:2015(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 2015

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ISO/DIS 2903:2015(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, 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
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ii © ISO 2015 – All rights reserved

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ISO/DIS 2903:2015
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 2903 was prepared by Technical Committee ISO/TC 1, Screw Threads.
This third edition cancels and replaces the second edition (ISO 2903:1993), Clauses 1, 13 and 14, and Table
7 of which have been technically revised.


iv © ISO 2015 – All rights reserved

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DRAFT INTERNATIONAL STANDARD ISO/DIS 2903:2015 (E)

ISO metric trapezoidal screw threads — Tolerances
1 Scope
This International Standard specifies a tolerance system for metric trapezoidal screw threads in accordance
with ISO 2902. The tolerances refer to the design profile in accordance with ISO 2901.
The tolerance system does not apply to trapezoidal screw threads with special requirements on axial
displacement, for example machine tool lead and feed screws and nuts.
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 965-1, ISO general purpose metric screw threads —Tolerances — Part 1: Principles and basic data
ISO 2901, ISO metric trapezoidal screw threads — Basic and design profiles
ISO 2902, ISO metric trapezoidal screw threads — General plan
ISO 5408, Screw threads — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5408 apply.
4 Symbols
For the purposes of this document, the following symbols apply.
D basic major diameter of internal thread
4
D nominal diameter (internal thread)
D basic pitch diameter of internal thread
2
D basic minor diameter of internal thread
1
d basic major diameter of external thread (nominal diameter)
d basic pitch diameter of external thread
2
d basic minor diameter of external thread
3
P pitch
Ph lead
N designation for normal group of thread engagement
© ISO 2015 – All rights re
...

INTERNATIONAL ISO
STANDARD 2903
Third edition
2016-09-01
ISO metric trapezoidal screw
threads — Tolerances
Filetages métriques trapézoïdaux ISO — Tolérances
Reference number
ISO 2903:2016(E)
©
ISO 2016

---------------------- Page: 1 ----------------------
ISO 2903:2016(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]
[e-mail]
www.iso.org
ii © ISO 2016 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 2903:2016(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 1
5 Tolerance system . 2
6 Tolerance positions . 2
7 Tolerance grades . 4
8 Length groups of thread engagement . 9
9 Recommended tolerance classes .11
10 Multiple-start threads .11
11 Formulae .12
11.1 General .12
11.2 Fundamental deviations .12
11.3 Crest diameter tolerances .13
11.3.1 Tolerances for major diameter of external thread (T ) .13
d
11.3.2 Tolerances for minor diameter of internal thread (T ) .13
D1
11.4 Pitch diameter tolerances .13
11.4.1 Tolerances for pitch diameter of external thread (T ) .13
d2
11.4.2 Tolerances for pitch diameter of internal thread (T ) .13
D2
11.5 Tolerances for minor diameter of external thread (T ) .
...

NORME ISO
INTERNATIONALE 2903
Troisième édition
2016-09-01
Filetages métriques trapézoïdaux
ISO — Tolérances
ISO metric trapezoidal screw threads — Tolerances
Numéro de référence
ISO 2903:2016(F)
©
ISO 2016

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ISO 2903:2016(F)

DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2016, Publié en Suisse
Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni utilisée
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l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.
ISO copyright office
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CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
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[e-mail]
www.iso.org
ii © ISO 2016 – Tous droits réservés

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ISO 2903:2016(F)

Sommaire Page
Avant-propos .iv
1 Domaine d’application . 1
2 Références normatives . 1
3 Termes et définitions . 1
4 Symboles . 1
5 Système de tolérance . 2
6 Positions de tolérance . 2
7 Qualités de tolérances . 4
8 Groupes de longueur en prise du filetage .10
9 Classes de tolérance recommandées .12
10 Filetages à plusieurs filets .12
11 Formules .13
11.1 Généralités .13
11.2 Ecarts fondamentaux .13
11.3 Tolérances sur les diamètres au sommet .14
11.3.1 Tolérances sur le diamètre extérieur du filetage extérieur (T ) .14
d
11.3.2 Tolérances sur le diamètre intérieur du filetage intérieur (T ) .14
D1
11.4 Tolérances sur les diamètres sur flancs.14
11.4.1 Tolérances sur le diamètre sur flancs du filetage extérieur (T ) .14
d2
11.4.2 Tolérances sur le diamètre sur flancs du filetage intérieur (T ) .14
D2
11.5 Tolérances sur le diamètre intérieur du filetage extérieur (T ) .15
d3
11.6 Groupes de longueur en prise du filetage .
...