INTERNATIONAL STANDARD ISO 6789-1 First edition 2017-02 Assembly tools for screws and nuts — Hand torque tools — Part 1: Requirements and methods for design conformance testing and quality conformance testing: minimum requirements for declaration of conformance Outils de manoeuvre pour vis et écrous — Outils dynamométriques commande manuelle — Partie 1: Exigences et méthodes d’essai pour vérifier la formité de conception et la formité de qualité: exigences minimales pour déclaration de formité Reference number ISO 6789-1:2017(E) © ISO 2017 ISO 6789-1:2017(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2017, Published in Switzerland All rights reserved Unless otherwise specified, no part o f 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 o f the requester ISO copyright o ffice Ch de Blandonnet • 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 ISO 6789-1:2017(E) Contents Page Foreword iv Introduction vi Scope Normative references Terms, definitions and symbols Classification Requirements 5.1 Design conformance testing 5.1.1 General 5.1.2 Maximum torque values 5.1.5 Maximum permissible deviation 5.1.6 Overloading test 5.1.7 Endurance test 5.1.8 Effect of geometric changes f 5.3 Conformance test during use Torque measurement 6.2 Application of torque 6.3 Ambient conditions 6.4 Measurement requirements 6.5 Measurement sequence 11 6.5.1 General 11 11 11 Calculation of deviation 12 7.1 General 12 7.2 Calculation example 12 7.3 Calculation example 13 Declaration of conformance 14 Marking 15 Annex A (normative) Examples of indicating torque tools (Type I) 16 Annex B (normative) Examples of setting torque tools (Type II) 17 Annex C (informative) Measurement sequence flowchart for torque tools 19 Bibliography 22 Terms and definitio ns Symb o ls , des ignatio ns and units S p ecified to rque range S cales , dials and dis p lays Quality co n o rmance tes ting 6.1 To rque meas urement sys tem 6.5 I ndicating to rque to o ls , Typ e I 6.5 S etting to rque to o ls , Typ e I I © ISO 2017 – All rights reserved iii ISO 6789-1:2017(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work o f 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 o f electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the different approval criteria needed for the di fferent types o f ISO documents should be noted This document was dra fted in accordance with the editorial rules of the ISO/IEC Directives, Part (see www.iso org/directives) Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f patent rights ISO shall not be held responsible for identi fying any or all such patent rights Details o f any patent rights identified during the development o f 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 in formation given for the convenience o f users and does not constitute an endorsement For an explanation on the voluntary nature o f standards, the meaning o f ISO specific terms and expressions related to formity assessment, as well as in formation 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 29, Small tools, Subcommittee SC 10, Assembly tools for screws and nuts, pliers and nippers This first edition o f ISO 6789-1, together with ISO 6789-2, 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 This document specifies the requirements for design and manu facture including the content o f a declaration o f formance ISO 6789-2 specifies the requirements for traceable certificates o f calibration It includes a method for calculation o f uncertainties and provides a method for calibration of the torque measurement device used for calibrating hand torque tools b) The output drive designation of torque tools is expanded to include hexagonal and other output drives c) The definition o f the torque range o f the tools has been changed d) The rate o f loading (shown by the time to achieve the last 20 %) has been changed e) The importance of avoiding parasitic forces has been emphasized f ) Explanatory flowcharts for the measurement sequence o f di fferent torque tools have been added in Annex C g) The requirement for a “declaration of conformance” that the torque tool conforms with this document has been added h) The requirement for a “certificate o f calibration” has been removed, recognizing that manu facturers’ calibration certificates have not previously contained enough in formation to be traceable calibration certificates i) iv ISO 6789 has been editorially updated and restructured © ISO 2017 – All rights reserved I SO - : (E) Figures B.2, B.3, B.5 and B.6 have been changed A list of all parts in the ISO 6789 series can be found on the ISO website j) © ISO 2017 – All rights reserved v ISO 6789-1:2 017(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 This document continues to provide designers and manufacturers with relevant minimum requirements for the development, production and documentation of hand torque tools ISO 6789-2 provides detailed methods for calculation of uncertainties and requirements for calibrations This will allow users o f calibration services to more easily compare the calibrations from di fferent laboratories Additionally, minimum requirements for the calibration o f torque measurement devices are described in ISO 6789-2:2017, Annex C vi © ISO 2017 – All rights reserved INTERNATIONAL STANDARD ISO 6789-1:2017(E) Assembly tools for screws and nuts — Hand torque tools — Part 1: Requirements and methods for design conformance testing and quality conformance testing: minimum requirements for declaration of conformance Scope T h i s c u ment s p e ci fie s the forma nce te s ti ng and marki ng re qu i rements for control le d for h and torque to ol s u s e d tighten i ng o f s crews a nd nuts I t a l s o s p e c i fie s the m i n i mu m re qu i rements of conformance for hand torque tools for de claration T h i s c u ment appl ie s to h and torque to ol s wh ich are cla s s i fie d a s i nd ic ati ng torque to ol s ( Typ e I ) and s e tti ng torque to ol s ( Typ e I I ) NO TE H a nd torque to ol s covere d b y th i s c u ment a re tho s e identi fie d i n I S O 170 : 0 b y re ference nu mb ers 0 1 , 0 1 a nd 0 , 0 a nd 0 14 , 0 I S O 170 i s c u r rentl y 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 T h i s c ument e s no t s p e ci fy re qu i rements o f c a l ibration cer ti fic ate s are described in ISO 6789-2 for hand torque to ol s T he s e Normative references T he fol lowi ng c u ments are re ferre d to i n the tex t i n s uch a way th at s ome or a l l o f thei r content s titute s re qu i rements o f th i s c u ment For date d re ference s , on ly the e d ition cite d app l ie s For u ndate d re ference s , the late s t e d ition o f the re ference d c ument (i nclud i ng a ny amend ments) appl ie s ISO 1173, Assembly tools for screws and nuts — Drive ends for hand- and machine-operated screwdriver bits and connecting parts — Dimensions, torque testing ISO 1174-1, Assembly tools for screws and nuts — Driving squares — Part 1: Driving squares for hand socket tools ISO 6789-2:2017, Assembly tools for screws and nuts — Hand torque tools — Part 2: Requirements for calibration and determination o f measurement uncertainty ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories Terms, definitions and symbols 3.1 Terms and definitions For the pu r p o s e s o f th i s c u ment, the fol lowi ng term s and defi n ition s 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 ISO 6789-1:2017(E) 3.1.1 design conformance test technical examination o f formance with those requirements to be met during design or modification of hand torque tools 3.1.2 quality conformance test technical examination of conformance with those requirements to be met during manufacture of hand torque tools 3.1.3 declaration of conformance documented in formation provided by the manu facturer that the torque tool complies with the requirements of this document 3.1.4 maximum permissible deviation maximum value of relative measurement deviation of the observed torque value on the torque measurement device measured as a percentage of the target torque value on the torque tool Note to entry: Sometimes the term “accuracy” is still used in place o f the term “maximum permissible deviation” which is, however, not technically correct The concept “measurement accuracy” is not a quantity and is not given a numerical quantity value A measurement is said to be more accurate when it o ffers a smaller measurement deviation Note to entry: Maximum permissible deviation is di fferent from measurement error which is used in ISO 6789-2 and defined in ISO/IEC Guide 99 3.1.5 torque measurement system combination o f a torque measurement device and the loading system for application o f torque that acts as the measurement standard for the hand torque tool Note to entry: A calibration system as defined in ISO 6789-2 can also be used as a torque measurement system in this document 3.1.6 torque measurement device working measurement standard provided either mechanically or by an electronic torque transducer and display 3.1.7 indicating torque tool (Type I) tool that indicates by means o f a mechanical scale, dial or electronic display, the value o f torque exerted by the tool at the output drive 3.1.8 setting torque tool (Type II) tool sensing torque transmitted by comparing the torque applied with a sel f-contained standard and signalling the transmission o f the pre-selected value by a physical impulse, with or without audible signal, causing a temporary reduction in the torque applied 3.1.9 adjustable graduated torque tool (Type II, Class A, Class D and Class G) tool designed to be adjusted by the user, which has a scale or a display to assist adjustment 3.1.10 adjustable non-graduated torque tool (Type II, Class C and Class F) tool designed to be adjusted by the user with the aid o f a torque measurement system © ISO 2017 – All rights reserved ISO 6789-1:2 017(E) 3.1.11 tool not designed to be adjusted by the user, i.e having a single setting t o r q u 3.2 e t o o l w i t h f i x e d a d j u s t m e n t ( T y p e I I , C l a s s B a n d C l a s s E ) Symbols, designations and units The designations used in this document are indicated in Table Table — Symbols, designations and units Symbol Designation Relative deviation of the torque tool from the target torque ad Xo C l a s % Value o f torque desired, which may be the indicated, set, nominal value, depending on N ⋅ m the type and class o f the torque tool Observed value shown by the torque measurement device N⋅m Xt Unit s i f i c a t i o n The hand torque tools to which this document applies are classified as follows a) Indicating torque tools (Type I; see Annex A): 1) Class A: Wrench, torsion or flexion bar; 2) Class B: Wrench, rigid housing, with scale or dial or display; 3) Class C: Wrench, rigid housing and electronic measurement; 4) Class D: Screwdriver, with scale or dial or display; 5) Class E: Screwdriver, with electronic measurement; b) Setting torque tools (Type II; see Annex B): 1) Class A: Wrench, adjustable, graduated or with display; 2) Class B: Wrench, fixed adjustment; 3) Class C: Wrench, adjustable, non-graduated; 4) Class D: Screwdriver, adjustable, graduated or with display; 5) Class E: Screwdriver, fixed adjustment; 6) Class F: Screwdriver, adjustable, non-graduated; 7) Class G: Wrench, flexion bar, adjustable, graduated Requirements 5.1 5.1.1 Design conformance testing General The manu facturer shall veri fy that the torque tool is in formity with 5.1.2 to 5.1.8 © ISO 2017 – All rights reserved ISO 6789-1:2017(E) 5.1.2 Maximum torque values The size of the output drive limits the maximum torque value of the respective torque tool The assignment is carried out according to the values given in Table For outputs not specified in Table 2, the size o f the output drive is determined by the maximum torque o f the respective torque tool and shall comply with the requirements given in 5.1.6 and 5.1.8 Table — Maximum torque values of the torque tool Square output drive a b 5.1.3 nominal size a — — — 6,3 — 10 — 12,5 20 25 Hexagonal output drive nominal sizeb 5,5 6,3 — 11,2 12,5 — — Dimensions in accordance with ISO 1174-1 Dimensions in accordance with ISO 1173 Maximum torque value N⋅m 10 25 30 70 135 200 340 000 100 Specified torque range The requirements and methods in this document cover a specified torque range, where the range depends on type and class o f the torque tool The torque range or value is selected for the different torque tools as follows — Indicating torque tools o f Type I (Classes A, B and D): From the lowest marked value to 100 % o f the maximum torque value of the respective tool — Indicating torque tools o f Type I (Classes C and E): As specified by the manu facturer — Setting torque tools o f Type II (Classes A, D and G): From the lowest marked value to 100 % o f the maximum torque value of the respective tool — Setting torque tools o f Type II (Classes B, C, E and F): As specified by the manu facturer 5.1.4 Scales, dials and displays For scales and dials, the increment between two graduation marks shall not exceed % o f the maximum torque value of the torque tool For electronic displays, the resolution shall not exceed 1/4 o f the maximum permissible relative deviation of the torque tool at each target value For indicating torque tools o f Type I (Classes A, B and D), the scales or dials shall be marked with a zero position The range between zero and the lowest specified torque value shall be marked on or near the dial or scale in a way to make clear to the user that this range is not within the specified torque range Alternatively, the scale, dial or display shall be identified in some way to indicate the specified torque range to the user © ISO 2017 – All rights reserved ISO 6789-1:2017(E) a) Wrench in a horizontal position b) Wrench in 5° offset Key a Line contact, marked loading point or centre of the hand hold position of the grip Figure — Testing of a wrench in a horizontal position (top view) Figure — Testing of a torque screwdriver and T-handle torque wrench in horizontal and vertical positions 10 © ISO 2017 – All rights reserved ISO 6789-1:2 017(E) 6.5 6.5.1 Measurement sequence General Where the torque measurement device has not been continuously operating during the previous hour, three loadings to the maximum torque of the torque tool in the measurement direction are required and the torque measurement device shall then be set to zero Torque tools with electronic measurement shall be powered during the whole measurement sequence The measurement is carried out separately for each direction For each direction o f operation, the torque tool shall be preloaded three times at its maximum specified torque value without recording The number of recorded measurements shall be according to Table Table — Number of recorded measurements Type of torque tool Class of torque tool Number of recorded measurements at each target torque value Type I All Type II A, D and G Type II B, C, E and F 10 Torque tools which are covered by both classifications Type I and Type II shall be measured for both Types, unless the manu facturer has stated a pre ferred Type for this tool, in which case the maximum permissible relative deviation for the other Type also needs to be stated by the manu facturer 6.5.2 Indicating torque tools, Type I Indicating torque tools (Type I, all Classes) shall first be measured at the lowest specified torque value of the measurement range (see 5.1.3 ) then at approximately 60 % and finally at 100 % of the torque tool’s maximum value For indicating torque tools (Type I, all Classes), a fter the three preloadings at the maximum torque o f the tool, all load on the torque tool and the torque measurement system shall be removed A fter a waiting period o f at least s, the pointer or electronic display o f the torque tool and the torque measurement device shall be set to zero where such a facility exists Then, the further number o f recorded measurements shall be as specified in Table For indicating torque tools (Type I) with electronic display, the readings shall only be recorded a fter the display has stabilized 6.5.3 Setting torque tools, Type II Setting torque tools (Type II, Classes A, D and G) shall first be measured at the lowest specified torque value of the measurement range (see 5.1.3 ) then at approximately 60 % and finally at 100 % of the torque tool’s maximum value For setting torque tools (Type II, all Classes), a fter the three preloadings at the maximum torque o f the tool, all load on the torque tool and the torque measurement system shall be removed A fter a waiting period o f at least s, the pointer or electronic display o f the torque measurement device shall be set to zero where such a facility exists Then, the further number o f recorded measurements shall be as specified in Table Setting torque tools (Type II, Classes A, D and G) shall be set to each target value starting from a lower value I f the target value is exceeded, the tool shall be set back to a lower value be fore re-adjustment to the target value Setting torque tools (Type II, Classes C and F) shall be measured 10 times in succession at the lowest limit value or nominal torque pre-set value © ISO 2017 – All rights reserved 11 ISO 6789-1:2017(E) Setting torque tools (Type II, Classes B and E) shall be measured 10 times in succession at the nominal fixed value Calculation of deviation 7.1 General The evaluation o f the relative measurement deviation shall be made by Formula (1) ad = where 7.2 ( Xo − X t ) Xt (1) × 100 ad is the calculated relative deviation o f the torque tool in per cent (%) for the target torque; Xt is for indicating tools torque tools Type I the indicated value; Xt is for setting torque tools Type II (Classes A, D and G), the torque value set on scale or display; Xt is for setting torque tools Type II (Classes B and E), the nominal torque value set; Xt is for setting torque tools Type II (Classes C and F), the lowest limit value or nominal torque preset value in accordance with 6.5 ; Xo is the value observed by the torque measurement device Calculation example Calculation o f the relative deviation o f indicating torque tools (Type I) and setting torque tools [Type II, except Type II (Class B, C, E and F)]: — indicated value o f dial, mechanical scale or display [indicating torque tool, Type I (Classes A, B, C, D and E)], or — set value o f mechanical scale or display [setting torque tool, Type II (Classes A, D and G)], or — nominal value [setting torque tool, Type II (Classes A, D and G)]: Xt = 100 N⋅m — observed values (determined by the torque measurement device): Xo1 = 104,0 N⋅m Xo2 = 96,5 N⋅m Xo3 = 102,6 N⋅m Xo4 = 99,0 N⋅m Xo5 = 101,0 N⋅m — calculated relative deviations o f the torque tool in %; see Formula (1): 12 © ISO 2017 – All rights reserved ISO 6789-1:2017(E) 7.3 a d1 = ( 104 , − 100 ) × 100 = +4 , 100 a d2 = ( 96 , − 100 ) × 100 = −3 , 100 a d3 = ( 102 , − 100 ) × 100 = +2 , 100 a d4 = ( 99 − 100 ) × 100 = − , 100 a d5 = ( 101 − 100 ) × 100 = +1 ,0 100 Calculation example C a lc u l ation o f the relative deviation o f s e tti ng torque to ol s , adj u s table, non- graduate d [ Typ e I I (C la s s B , C , E and F ) ] : — nom i na l va lue s e t [s e tti ng torque to ol, Typ e I I (C la s s e s B a nd E ) ] or — lowe s t s p e c i fie d torque va lue or pre - s e t va lue [s e tti ng torque to ol , Typ e I I (C la s s e s C and F ) ] : Xt = 10 N⋅ m — ob s er ve d va lue s (de term i ne d by the torque me as u rement device) : Xo1 = 10 4, N⋅ m Xo2 = 103 , N⋅ m Xo3 = 102 , N⋅ m Xo4 = 10 , N⋅ m Xo5 = 101 , N⋅ m Xo6 = 101 , N⋅ m Xo7 = 101 ,7 N⋅ m Xo8 = 101 ,9 N⋅ m Xo9 = 102 , N⋅ m Xo10 = 102 , — N⋅ m c a lcu l ate d relative devi ation s o f the torque to ol s i n % : a d1 = ( 104 , − 100 ) × 100 = + ,0 100 © ISO 2017 – All rights reserved 13 ISO 6789-1:2017(E) a d2 = ( 10 3, − 100 ) × 100 = +3 , 100 a d3 = ( 102 , − 100 ) × 100 = +2 , 100 a d4 = 102 , − 100 ) × 100 = +2 , 100 a d5 = ( 101 , − 100 ) × 100 = +1 , 100 a d6 = ( 101 , − 100 ) × 100 = +1, 100 a d7 = ( 101 , − 100 , ) × 100 = +1 , 100 , a d8 = ( 101 , − 100 ) × 100 = +1 , 100 a d9 = ( 102 , − 100 ) × 100 = +2 , 100 a d10 = ( 102 , − 100 ) × 100 = +2, 100 Declaration of conformance The declaration of conformance shall contain at least the following information: a) s tatement that it i s a de cla ration o f forma nce i n accord ance with th i s c u ment; b) identi fic ation (typ e a nd s eria l nu mb er) o f the torque to ol; c) where an interchangeable element has been used with the tool, the effective length or dimension of th at i ntercha nge able element sh a l l b e re corde d; d) where a n ex ten s ion h and le s b e en u s e d with the torque to ol, it sh a l l b e re corde d; e) s p e ci fie d torque range or fi xe d torque va lue o f the torque to ol; f) identi fic ation (typ e a nd s eria l nu mb er) o f the torque me a s u rement device; g) d i re c tion(s) o f op eration; h) ambient temp eratu re and s tatement on hu m id ity; i) date o f the me as u rement; j) name o f the re s p on s ible p ers on; k) maximum permissible relative deviation according to 5.1.5 l) observed values at each target torque (see 6.5 m) statement whether or not the observed values fall within the maximum permissible relative ; ); deviation as defi ne d i n l i s t item k) ; 14 © ISO 2017 – All rights reserved ISO 6789-1:2017(E) n) m a x i mu m me a s u re me nt e r ro r a nd me a s u re me nt u nc e r ta i nt y i nte r va l of the to rque me a s u re me n t de v i ce ; o) statement that the measurement error of the torque measurement device is less than 1/4 of the ma xi mu m p erm i s s ible relative deviation o f the torque to ol; p) for Marking to ol s with flexible he ad , a s tatement th at the perpendicular to the axis of the tool re s u lt i s va l id on ly i f the me a s u ri ng a xi s is D u ri ng manu fac tu re, h and torque to ol s s l l b e ma rke d, p ermanently a nd legibly, at le as t with the following information: a) the ma xi mu m and m i ni mu m torque va lue s or [for Typ e I I (C la s s e s B a nd E ) ] the fi xe d adj u s te d torque va lue; b) c) the u n it(s) o f torque; Typ e I I (C l as s e s C and F ) may a l s o b e marke d i n a non-p erma nent way with the nom i na l torque pre s e t va lue i n u s er s p e ci fie d u n its; d) the d i re c tion o f op eration (for to ol s c ap able o f op erati ng i n one d i re c tion on ly) ; e) the f) the name or trademark o f the ma nu fac tu rer or re s p on s ible s uppl ier; g) force where lo ad i ng p oi nt [e xcep t Typ e I (C l as s e s D and E ) and Typ e I I (C la s s e s D, E a nd F ) ] ; accomp an ie d by a de cl aration o f formance , the torque to ol sh a l l h ave a s eri a l or identi fic ation nu mb er I f ne ce s s ar y, an identi fication nu mb er sh a l l b e as s igne d © ISO 2017 – All rights reserved 15 ISO 6789-1:2017(E) Annex A (normative) Examples of indicating torque tools (Type I) F i g u r e A — C l a s s A : w r e n c h , t o r s i o n o r f l e x i o n b a r Figure A.2 — Class B: wrench, rigid housing, with scale or dial or display Figure A.3 — Class C: wrench, rigid housing and electronic measurement Figure A.4 — Class D: screwdriver, with scale or dial or display Figure A.5 — Class E: screwdriver, with electronic measurement 16 © ISO 2017 – All rights reserved ISO 6789-1:2017(E) Annex B (normative) Examples of setting torque tools (Type II) Figure B.1 — Class A: wrench, adjustable, graduated or with display F i g u r e B — C l a s s B : w r e n c h f i x e d a d j u s t m e n t Figure B.3 — Class C: wrench, adjustable, non-graduated Figure B.4 — Class D: screwdriver, adjustable, graduated or with display F i g © ISO 2017 – All rights reserved u r e B — C l a s s E : s c r e w d r i v e r , f i x e d a d j u s t m e n t 17 ISO 6789-1:2017(E) Figure B.6 — Class F: screwdriver, adjustable, non-graduated F 18 i g u r e B — C l a s s G : w r e n c h f l e x i o n b a r , a d j u s t a b l e , g r a d u a t e d © ISO 2017 – All rights reserved ISO 6789-1:2017(E) Annex C (informative) M e a s u r e m e n t s e q u e n c e f l o w c h a r t f o r t o r q u e t o o l s C.1 Indicating torque tools (Type I) Key CW clockwise direction CCW counter-clockwise direction a Torque measurement device and torque tool shall be allowed to attain the ambient temperature prior to measurement © ISO 2017 – All rights reserved 19 ISO 6789-1:2017(E) C.2 Setting Torque tools [Type II (Classes A, D and G)] Key CW clockwise direction CCW counter-clockwise direction a Torque measurement device and torque tool shall be allowed to attain the ambient temperature prior to measurement 20 © ISO 2017 – All rights reserved ISO 6789-1:2 017(E) C.3 Setting torque tools [Type II (Classes B, C, E and F) ] Key CW clockwise direction CCW counter-clockwise direction a Torque measurement device and torque tool shall be allowed to attain the ambient temperature prior to measurement © ISO 2017 – All rights reserved 21 ISO 6789-1:2017(E) Bibliography [1] I S O 170 : 0 , [2 ] I S O 01 , [3 ] [4] 22 I S O/I E C Assembly tools for screws and nuts — Designation and nomenclature Quality management systems — Requirements Gu ide 9, International vocabulary o f metrology — Basic and general concepts and associated terms (VIM) I S O/I E C Guide -3 , Uncertainty o f measurement — Part 3: Guide to the expression o f uncertainty in measurement (GUM:1995) © ISO 2017 – All rights reserved I SO - : (E ) ICS 25.140.30 Price based on 22 pages © ISO 2017 – All rights reserved