prEN ISO 6789-2

Assembly tools for screws and nuts - Hand torque tools - Part 2: Requirements for calibration and determination of measurement uncertainty (ISO/DIS 6789-2:2025)

This document specifies the method for the calibration of hand torque tools and describes the method of calculation of measurement uncertainties for the calibration.
It also specifies the minimum requirements for a certificate of calibration to this standard for hand torque tools.
The Annex C of this document specifies the minimum requirements for the calibration of the torque measurement device where the relative measurement uncertainty interval, W´md, is not already provided by a traceable calibration certificate.
This document applies to hand torque tools which are classified as indicating torque tools (Type I) and setting torque tools (Type II).
NOTE    Hand torque tools covered by this document are those identified in ISO 1703:2018 by reference numbers 7 1 00 01 0 to 7 1 00 14 0 inclusive.  Torque limiting hand torque tools do not yet have reference numbers and will not do so until the next revision of ISO 1703

Outils de manoeuvre pour vis et écrous - Outils dynamométriques à commande manuelle - Partie 2: Exigences d'étalonnage et détermination de l'incertitude de mesure (ISO/DIS 6789-2:2025)

ISO 6789-2:2017 spécifie la méthode d'étalonnage des outils dynamométriques à commande manuelle et décrit la méthode de calcul des incertitudes de mesure associées à l'étalonnage.
ISO 6789-2:2017 spécifie les exigences minimales relatives à l'étalonnage du dispositif de mesure de couple lorsque l'intervalle d'incertitude de mesure relative, W´md, n'est pas déjà fourni par un certificat d'étalonnage traçable.
L'ISO 6789 s'applique à l'étalonnage pas à pas (statique) et continu (quasi-statique) des dispositifs de mesure de couple, dont le couple est établi en mesurant la variation élastique d'un corps déformable ou une variable mesurée proportionnelle au couple.
ISO 6789-2:2017 s'applique aux outils dynamométriques à commande manuelle classés en tant qu'outils dynamométriques à lecture directe (Type I) et outils dynamométriques à déclenchement (Type II).
NOTE Les outils dynamométriques à commande manuelle couverts par le présent document sont ceux identifiés dans l'ISO 1703:2005 sous les numéros de référence 6 1 00 11 0, 6 1 00 11 1 et 6 1 00 12 0, 6 1 00 12 1 et 6 1 00 14 0, 6 1 00 15 0. L'ISO 1703 est en cours de révision. Dans la prochaine édition, les outils dynamométriques seront traités dans un article distinct, et du fait de cette modification, les numéros de référence changeront également et des numéros de référence supplémentaires seront ajoutés.

Orodja za vijake in matice - Ročna vrtilna orodja - 2. del: Zahteve za umerjanje in določanje merilne negotovosti (ISO/DIS 6789-2:2025)

General Information

• Status: Not Published
• Publication Date: 17-Jan-2027
• ICS: 25.140.30 - Hand-operated tools
• Technical Committee: CEN/SS I09 - Small tools
• Current Stage: 4060 - Closure of enquiry - Enquiry
• Start Date: 15-Sep-2025
• Completion Date: 15-Sep-2025
• Ref Project: oSIST prEN ISO 6789-2:2025 - Assembly tools for screws and nuts - Hand torque tools - Part 2: Requirements for calibration and determination of measurement uncertainty (ISO/DIS 6789-2:2025)

Relations

• Revises: EN ISO 6789-2:2017 - Assembly tools for screws and nuts - Hand torque tools - Part 2: Requirements for calibration and determination of measurement uncertainty (ISO 6789-2:2017)
• Effective Date: 05-Apr-2023

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2025
Orodja za vijake in matice - Ročna vrtilna orodja - 2. del: Zahteve za umerjanje in
določanje merilne negotovosti (ISO/DIS 6789-2:2025)
Assembly tools for screws and nuts - Hand torque tools - Part 2: Requirements for
calibration and determination of measurement uncertainty (ISO/DIS 6789-2:2025)
Outils de manoeuvre pour vis et écrous - Outils dynamométriques à commande
manuelle - Partie 2: Exigences d'étalonnage et détermination de l'incertitude de mesure
(ISO/DIS 6789-2:2025)
Ta slovenski standard je istoveten z: prEN ISO 6789-2
ICS:
25.140.30 Orodja za ročno uporabo Hand-operated tools
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 6789-2
ISO/TC 29/SC 10
Assembly tools for screws and
Secretariat: DIN
nuts — Hand torque tools —
Voting begins on:
Part 2: 2025-06-23
Requirements for calibration and
Voting terminates on:
2025-09-15
determination of measurement
uncertainty
Outils de manoeuvre pour vis et écrous — Outils
dynamométriques à commande manuelle —
Partie 2: Exigences d'étalonnage et détermination de l'incertitude
de mesure
ICS: 25.140.30
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
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.
Reference number
ISO/DIS 6789-2:2025(en)
DRAFT
ISO/DIS 6789-2:2025(en)
International
Standard
ISO/DIS 6789-2
ISO/TC 29/SC 10
Assembly tools for screws and
Secretariat: DIN
nuts — Hand torque tools —
Voting begins on:
Part 2:
Requirements for calibration and
Voting terminates on:
determination of measurement
uncertainty
Outils de manoeuvre pour vis et écrous — Outils
dynamométriques à commande manuelle —
Partie 2: Exigences d'étalonnage et détermination de l'incertitude
de mesure
ICS: 25.140.30
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2025
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
or ISO’s member body in the country of the requester.
NATIONAL REGULATIONS.
ISO copyright office
RECIPIENTS OF THIS DRAFT ARE INVITED
CP 401 • Ch. de Blandonnet 8
TO SUBMIT, WITH THEIR COMMENTS,
CH-1214 Vernier, Geneva
NOTIFICATION OF ANY RELEVANT PATENT
Phone: [phone]
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 6789-2:2025(en)
ii
ISO/DIS 6789-2:2025(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions .2
3.2 Symbols, designations and units .3
4 General requirements for torque calibration and angle calibration . 4
4.1 Calibration by the manufacturer of the torque tool .4
4.2 Calibration during use .4
4.3 Ambient conditions.5
4.4 Calibration system .5
5 Torque calibration - specific requirements . 6
5.1 Torque measurement - application .6
5.1.1 Orientation of torque tools to be calibrated .6
5.1.2 Loading methods for torque tools to be calibrated .8
5.2 Torque measurement – loading sequence .9
5.2.1 General .9
5.2.2 Preloading sequence .9
5.2.3 Loading sequence .10
5.3 Torque measurement - error . .10
5.4 Torque measurement - sources of uncertainty .11
5.4.1 General .11
5.4.2 Evaluation of Type B uncertainties due to the torque tool .11
5.4.3 Evaluation of Type A uncertainty due to the torque tool .17
6 Torque measurement - determination of the result .18
6.1 Determination of the relative standard measurement uncertainty, w .18
6.2 Determination of the relative expanded measurement uncertainty, W .19
6.3 Determination of the relative measurement uncertainty interval, W ‘ .19
7 Angle calibration – specific requirements . 19
7.1 Angle measurement -application .19
7.2 Angle measurement - loading sequence . 20
7.2.1 General . 20
7.2.2 Loading sequence . 20
7.2.3 Ratcheting function .21
7.3 Angle measurement .21
7.3.1 Measurement error .21
7.3.2 Error due to bending of the tool . 22
7.3.3 Evaluation of Type B angle measurement uncertainties due to the torque tool . 22
7.3.4 Evaluation of Type B angle measurement uncertainties due to the torque tool . 22
8 Angle measurement - determination of the result .23
8.1 Determination of the relative standard measurement uncertainty,w . 23
8.2 Determination of the relative expanded measurement uncertainty, W .24
8.3 Determination of the relative measurement uncertainty interval, W ‘ .24
9 Calibration certificate .24
Annex A (informative) Calculation example for an indicating torque tool (Type I) .26
Annex B (informative) Calculation example for a setting torque tool (Type II) .33
Annex C (informative) Minimum requirements for the calibration of the torque measurement
device and the estimation of its measurement uncertainty .39

iii
ISO/DIS 6789-2:2025(en)
Annex D (informative) Calculation example for a torque tool with angle .40
Bibliography .46

iv
ISO/DIS 6789-2:2025(en)
Foreword
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
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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
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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
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