SIST EN ISO 6789-2:2017

SLOVENSKI STANDARD
SIST EN ISO 6789-2:2017
01-maj-2017
1DGRPHãþD
SIST EN ISO 6789:2004
2URGMD]DYLMDNHLQPDWLFH5RþQDYUWLOQDRURGMDGHO=DKWHYH]DXPHUMDQMHLQ
GRORþDQMHPHULOQHQHJRWRYRVWL,62
Assembly tools for screws and nuts - Hand torque tools - Part 2: Requirements for
calibration and determination of measurement uncertainly (ISO 6789-2:2017)
Schraubwerkzeuge - Handbetätigte Drehmoment-Werkzeuge - Teil 2: Anforderungen an
die Kalibrierung und die Bestimmung der Messunsicherheit (ISO 6789-2:2017)
Outils de manoeuvre pour vis et écrous - Outils dynamométriques à commande
manuelle (ISO 6789-2:2017)
Ta slovenski standard je istoveten z: EN ISO 6789-2:2017
ICS:
25.140.30 2URGMD]DURþQRXSRUDER Hand-operated tools
SIST EN ISO 6789-2:2017 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST EN ISO 6789-2:2017

---------------------- Page: 2 ----------------------

SIST EN ISO 6789-2:2017


EN ISO 6789-2
EUROPEAN STANDARD

NORME EUROPÉENNE

March 2017
EUROPÄISCHE NORM
ICS 25.140.30 Supersedes EN ISO 6789:2003
English Version

Assembly tools for screws and nuts - Hand torque tools -
Part 2: Requirements for calibration and determination of
measurement uncertainly (ISO 6789-2:2017)
Outils de manoeuvre pour vis et écrous - Outils Schraubwerkzeuge - Handbetätigte
dynamométriques à commande manuelle - Partie 2: Drehmomentwerkzeuge - Teil 2: Anforderungen an die
Exigences d'étalonnage et détermination de Kalibrierung und die Bestimmung der
l'incertitude de mesure (ISO 6789-2:2017) Messunsicherheit (ISO 6789-2:2017)
This European Standard was approved by CEN on 14 January 2017.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 6789-2:2017 E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------

SIST EN ISO 6789-2:2017
EN ISO 6789-2:2017 (E)
Contents Page
European foreword . 3

2

---------------------- Page: 4 ----------------------

SIST EN ISO 6789-2:2017
EN ISO 6789-2:2017 (E)
European foreword
This document (EN ISO 6789-2:2017) has been prepared by Technical Committee ISO/TC 29 “Small
tools”.
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 2017, and conflicting national standards
shall be withdrawn at the latest by March 2018.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
This document supersedes EN ISO 6789:2003.
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, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 6789-2:2017 has been approved by CEN as EN ISO 6789-2:2017 without any
modification.


3

---------------------- Page: 5 ----------------------

SIST EN ISO 6789-2:2017

---------------------- Page: 6 ----------------------

SIST EN ISO 6789-2:2017
INTERNATIONAL ISO
STANDARD 6789-2
First edition
2017-02
Assembly tools for screws and nuts —
Hand torque tools —
Part 2:
Requirements for calibration and
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
Reference number
ISO 6789-2:2017(E)
©
ISO 2017

---------------------- Page: 7 ----------------------

SIST EN ISO 6789-2:2017
ISO 6789-2:2017(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. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved

---------------------- Page: 8 ----------------------

SIST EN ISO 6789-2:2017
ISO 6789-2:2017(E)

Contents Page
Foreword .iv
Introduction .v
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 . 2
4 Requirements for calibration . 4
4.1 Calibration during use . 4
4.2 Calibration method. 4
4.3 Calibration system . 4
5 Measurement error . 5
5.1 Calculation of the relative measurement error . 5
5.2 Exemplary calculations of the relative measurement error . 5
5.2.1 Example 1 . 5
5.2.2 Example 2 . 6
6 Sources of uncertainty . 7
6.1 General . 7
6.2 Evaluation of Type B uncertainties due to the torque tool . 8
6.2.1 Scale, dial or display resolution, r .8
6.2.2 Variation due to the reproducibility of the torque tool, b .
rep 10
6.2.3 Variation due to the interface between the torque tool and the
calibration system.11
6.2.4 Variation due to the variation of the force loading point, b .
l 12
6.3 Evaluation of Type A uncertainty due to the torque tool .13
6.3.1 General.13
6.3.2 Variation due to the repeatability of the torque tool, b .
re 13
7 Determination of the calibration result .13
7.1 Determination of the relative standard measurement uncertainty, w. 13
7.2 Determination of the relative expanded measurement uncertainty, W . 14
7.3 Determination of the relative measurement uncertainty interval, W’ . 14
8 Calibration certificate .15
Annex A (informative) Calculation example for an indicating torque tool (Type I) .16
Annex B (informative) Calculation example for a setting torque tool (Type II) .25
Annex C (normative) Minimum requirements for the calibration of the torque
measurement device and the estimation of its measurement uncertainty .34
Bibliography .41
© ISO 2017 – All rights reserved iii

---------------------- Page: 9 ----------------------

SIST EN ISO 6789-2:2017
ISO 6789-2:2017(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: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 29, Small tools, Subcommittee SC 10,
Assembly tools for screws and nuts, pliers and nippers.
This first edition of ISO 6789-2, together with ISO 6789-1, cancels and replaces ISO 6789:2003 which
has been technically revised with changes as follows.
a) ISO 6789:2003 has been divided into two parts. ISO 6789:2003 has become ISO 6789-1 which
specifies the requirements for design and manufacture including the content of a declaration of
conformance. This document specifies the requirements for traceable certificates of calibration.
It includes a method for calculation of uncertainties and provides a method for calibration of the
torque measurement device used for calibrating hand torque tools.
b) This document includes detailed methods for calculation of the uncertainty budget which shall be
performed for each individual tool.
c) This document includes example calculations that are provided for different types of torque tool.
d) Annex C provides requirements for calibrating the torque measurement device where the
calibration laboratory does not utilize a national standard giving such requirements.
A list of all parts in the ISO 6789 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved

---------------------- Page: 10 ----------------------

SIST EN ISO 6789-2:2017
ISO 6789-2:2017(E)

Introduction
The revision of ISO 6789:2003 has been designed to achieve the following improvements.
ISO 6789 has been split to provide two levels of documentation. It recognizes the different needs of
different users of the standard.
ISO 6789-1 continues to provide designers and manufacturers with relevant minimum requirements
for the development, production and documentation of hand torque tools.
This document provides detailed methods for calculation of uncertainties and requirements for
calibrations. This will allow users of calibration services to more easily compare the calibrations from
different laboratories. Additionally, minimum requirements for the calibration of torque measurement
devices are described in Annex C.
The purpose of this document is to define the requirements for a calibration in which the sources of
uncertainty are evaluated and used to define the range of values within which the readings probably
fall. Additional uncertainties may exist in the use of the torque tool. The evaluation of uncertainties
for each individual tool is time-consuming and where there are sufficient data to estimate the Type B
uncertainty components by statistical means, it is acceptable to use these values for a given model of
torque tool, providing that the uncertainty components are subject to periodic review.
© ISO 2017 – All rights reserved v

---------------------- Page: 11 ----------------------

SIST EN ISO 6789-2:2017

---------------------- Page: 12 ----------------------

SIST EN ISO 6789-2:2017
INTERNATIONAL STANDARD ISO 6789-2:2017(E)
Assembly tools for screws and nuts — Hand torque tools —
Part 2:
Requirements for calibration and determination of
measurement uncertainty
1 Scope
This document specifies the method for the calibration of hand torque tools and describes the method
of calculation of measurement uncertainties for the calibration.
This document specifies the minimum requirements for the calibration of the torque measurement
device where the relative measurement uncertainty interval, W´ , is not already provided by a
md
traceable calibration certificate.
ISO 6789 is applicable for the step by step (static) and continuous (quasi-static) calibration of torque
measurement devices, the torque of which is defined by measuring of the elastic form change of a
deformable body or a measured variable which is in proportion to the torque.
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 the ones identified in ISO 1703:2005 by reference
numbers 6 1 00 11 0, 6 1 00 11 1 and 6 1 00 12 0, 6 1 00 12 1 and 6 1 00 14 0, 6 1 00 15 0. ISO 1703 is currently
under revision. In the next edition, torque tools will be moved to an own clause, and with this change the
reference numbers will also change and additional reference numbers will be added.
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 6789-1:2017, Assembly tools for screws and nut — Hand torque tools — Part 1: Requirements and
methods for design conformance testing and quality conformance testing: minimum requirements for
declaration of conformance
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
3 Terms, definitions and symbols
For the purposes of this document, the terms and definitions given in ISO 6789-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
© ISO 2017 – All rights reserved 1

---------------------- Page: 13 ----------------------

SIST EN ISO 6789-2:2017
ISO 6789-2:2017(E)

3.1 Terms and definitions
3.1.1
Type A evaluation (of uncertainty)
method of evaluation of uncertainty by the statistical analysis of series of observations
Note 1 to entry: These data are taken directly from the measurements obtained during calibration of each torque
tool and cannot be prepared in advance.
[SOURCE: ISO/IEC Guide 98-3:2008, 2.3.2, modified — Note 1 to entry has been added.]
3.1.2
Type B evaluation (of uncertainty)
method of evaluation of uncertainty by means other than the statistical analysis of series of observations
[SOURCE: ISO/IEC Guide 98-3:2008, 2.3.3]
3.1.3
calibration system
combination of a measurement device and the loading system for application of torque that acts as the
measurement standard for the hand torque tool
Note 1 to entry: A calibration system can also be used as a torque measurement system as defined in ISO 6789-1.
3.1.4
measurement device
working measurement standard provided either mechanically or by an electronic torque transducer
and display
Note 1 to entry: A measurement device can also be referred to as a torque measurement device as defined in
ISO 6789-1.
3.1.5
reference measurement standard
measurement standard designated for the calibration of other measurement standards for quantities of
a given kind in a given organization or at a given location
[SOURCE: ISO Guide 99:2007, 5.6]
3.1.6
measurement error
measured quantity value minus a reference quantity value
[SOURCE: ISO/IEC Guide 99:2007, 2.16, modified — Notes 1 and 2 to entry have been omitted.]
3.2 Symbols, designations and units
The designations used in this document are indicated in Table 1.
Table 1 — Symbols, designations and units
Symbol Designation Unit
a Calculated relative measurement error of the torque tool for the calibration torque %
s
Mean value of the relative measurement error at each calibration torque %
a
s
b Stated measurement error of the measurement device N∙m
e
b Measurement error of the reference at the calibration torque N∙m
ref,e
b Stated relative measurement error of the measurement device %
ep
NOTE  While N∙m is the unit commonly used, the output signal can be detected in various units, e.g. voltage.
2 © ISO 2017 – All rights reserved

---------------------- Page: 14 ----------------------

SIST EN ISO 6789-2:2017
ISO 6789-2:2017(E)

Table 1 (continued)
Symbol Designation Unit
b Relative measurement error of the reference at the calibration torque %
ref,ep
Variation due to geometric effects of the interface between the output drive of the
b N∙m
int
torque tool and the calibration system
b Variation due to the variation of the force loading point N∙m
l
b Variation due to geometric effects of the output drive of the torque tool N∙m
od
b Variation due to the repeatability of the torque tool N∙m
re
Variation due to the repeatability of the measurement device in the same mounting
b N∙m
md,re
position
Variation due to the reproducibility of the torque tool (Type I and Type II Classes A,
b N∙m
rep
D and G only)
Variation due to the reproducibility of the measurement device in different mounting
b N∙m
md,rep
positions
b Measurement hysteresis error of the zero signal after loading N∙m
z
I Indicated value of measurement device without zero-value compensation N∙m
Indicated value of the zero signal 30 s after preload and prior to load in mounting
I N∙m
0
position
I Indicated value of the zero signal 30 s after unloading N∙m
z
Coverage factor k = 2 applied to the relative measurement uncertainty to achieve a
k —
confidence level of approximately 95 %
r Resolution of the display (Type I and Type II Classes A, D and G only) N∙m
r Resolution of the measurement device display N∙m
md
T Minimum limit of measuring range of the measurement device N∙m
A
T Maximum limit of measuring range of the measurement device N∙m
E
Minimum limit value of the measurement range of the torque tool declared by the
T N∙m
min
manufacturer
w Relative standard measurement uncertainty of the torque tool at the calibration torque %
Component of w due to geometric effects of the interface between the output drive
w %
int
of the torque tool and the calibration system
w Component of w due to the length variation of the force loading point %
l
Relative standard measurement uncertainty of the measurement device at the
w %
md
calibration torque
w Combined relative standard measurement uncertainty of the measurement device %
md,c
w Relative standard measurement uncertainty of the measurement device transducer %
md,t
w Relative standard measurement uncertainty of the measurement device display %
md,d
w Component of w due to geometric effects of the output drive of the torque tool %
od
Relative standard measurement uncertainty due to resolution of the display of the
w %
r
torque tool (Type I and Type II Classes A, D and G only)
Relative standard measurement uncertainty due to resolution of the measurement
w %
md,r
device display
w Component of w due to repeatability of the torque tool %
re
w Component of w due to repeatability of the measurement device %
md,re md
Component of w due to reproducibility of the torque tool (Type I and Type II Classes
w %
rep
A, D and G only)
w Component of w due to reproducibility of the measurement device %
md,rep md
Component of w due to the measurement hysteresis error of the zero signal of the
md
w %
md,z
measurement device
NOTE  While N∙m is the unit commonly used, the output signal can be detected in various units, e.g. voltage.
© ISO 2017 – All rights reserved 3

---------------------- Page: 15 ----------------------

SIST EN ISO 6789-2:2017
ISO 6789-2:2017(E)

Table 1 (continued)
Symbol Designation Unit
W Relative expanded measurement uncertainty of the torque tool at the calibration torque %
W′ Relative measurement uncertainty interval of the torque tool at the calibration torque %
Relative expanded measurement uncertainty of the measurement device at the
W %
md
calibration torque
Relative measurement uncertainty interval of the measurement device at the
W′ %
md
calibration torque
W Relative expanded measurement uncertainty of the reference measurement standard %
ref
W′ Relative measurement uncertainty interval of the reference measurement standard %
ref
X Indicated value of measurement device with zero-value compensation N∙m
X Target indicated, set or nominal value depending on the type and class of the torque tool N∙m
a
X Minimum value of X observed during different mounting positions N∙m
min
X Maximum value of X observed during different mounting positions N∙m
max
X Reference value determined by the measurement device N∙m
r
Mean reference value determined by the measurement device N∙m
X
r
X Reference value determined by the reference device N∙m
ref
NOTE  While N∙m is the unit commonly used, the output signal can be detected in various units, e.g. voltage.
4 Requirements for calibration
4.1 Calibration during use
If the user utilizes procedures for the control of test devices, torque tools shall be included in these
procedures. The interval between calibrations shall be chosen on the basis of the factors of operation
such as required maximum permissible measurement error, frequency of use, typical load during
operation as well as ambient conditions during operation and storage conditions. The interval shall
be adapted according to the procedures specified for the control of test devices and by evaluating the
results gained during successive calibrations.
If the user does not utilize a control procedure, a period of 12 months, or 5 000 cycles, whichever occurs
first, may be taken as default values for the interval between calibrations. The interval starts with the
first use of the torque tool.
Shorter interval between calibrations may be used if required by the user, their customer or by
legislation.
The torque tool shall be calibrated when it has been subjected to an overload greater than the values
given in ISO 6789-1:2017, 5.1.6, after repair, or after any improper handling which might influence the
torque tool performance and the fulfilment of the quality conformance requirements.
4.2 Calibration method
The method for the calibration of the torque tools shall be in accordance with the measurement method
of ISO 6789-1:2017, Clause 6. Additionally, the requirement for the torque measurement device defined
in ISO 6789-1:2017, 6.1 is replaced by 4.3.
4.3 Calibration system
The calibration system shall be chosen to be suitable for the measurement of the specified range of the
torque tool.
4 © ISO 2017 – All rights reserved

---------------------- Page: 16 ----------------------

SIST EN ISO 6789-2:2017
ISO 6789-2:2017(E)

At each target value, the relative uncertainty interval, W′ , of the measurement device shall not exceed
md
1/4 of the expected maximum relative uncertainty interval of the torque tool, W′.
The measurement device shall have a valid calibration certificate issued by a laboratory meeting
the requirements of ISO/IEC 17025. Alternatively, the measurement device shall be calibrated by a
laboratory maintaining the national measurement standard.
If the user does not utilize a control procedure, a period of 24 months shall be the maximum interval
between calibrations.
The measurement device shall be re-calibrated if it was exposed to an overload larger than 20 % of
T , after a repair has been carried out or after an improper use which can influence the measurement
E
uncertainty.
5 Measurement error
5.1 Calculation of the relative measurement error
The calibration values shall be measured and recorded according to the requirements in
ISO 6789-1:2017, 6.5.
The evaluation of the relative measurement error is calculated using Formula (1):
()XX−×100
ar
a = (1)
s
X
r
The mean value of the
...