Metallic materials - Calibration and verification of static uniaxial testing machines - Part 1: Tension/compression testing machines - Calibration and verification of the force-measuring system (ISO 7500-1:2018)

ISO 7500-1:2018 specifies the calibration and verification of tension/compression testing machines.
The verification consists of:
- a general inspection of the testing machine, including its accessories for the force application;
- a calibration of the force-measuring system of the testing machine;
- a confirmation that the performance properties of the testing machine achieve the limits given for a specified class.
NOTE This document addresses the static calibration and verification of the force-measuring systems. The calibration values are not necessarily valid for high-speed or dynamic testing applications. Further information regarding dynamic effects is given in the Bibliography.
CAUTION Some of the tests specified in this document involve the use of processes which can lead to a hazardous situation.

Metallische Werkstoffe - Kalibrierung und Überprüfung von statischen einachsigen Prüfmaschinen - Teil 1: Zug- und Druckprüfmaschinen - Kalibrierung und Überprüfung der Kraftmesseinrichtung (ISO 7500-1:2018)

Dieses Dokument legt die Kalibrierung und Überprüfung von Zug- und Druckprüfmaschinen fest.
Die Überprüfung besteht aus:
- einer allgemeinen Inspektion der Prüfmaschine einschließlich der Maschinenteile für die Kraftauf-bringung;
- einer Kalibrierung der Kraftmesseinrichtung der Prüfmaschine;
- einer Bestätigung, dass die ermittelten Eigenschaften der Prüfmaschine die für eine festgelegte Klasse angegebenen Grenzwerte erreichen.
ANMERKUNG Dieses Dokument betrifft die statische Kalibrierung und Überprüfung von Kraftmesseinrichtungen. Die Kalibrierergebnisse sind nicht notwendigerweise für Anwendungen für hochgeschwindigkeits- oder dynamische Prüfungen gültig. Weitere Informationen bezüglich dynamischer Effekte sind in den Literaturhinweisen angegeben.
ACHTUNG - Bei einigen der in diesem Dokument festgelegten Prüfungen werden Prozesse angewendet, die zu gefährlichen Situationen führen können.

Matériaux métalliques - Étalonnage et vérification des machines pour essais statiques uniaxiaux - Partie 1: Machines d'essai de traction/compression - Étalonnage et vérification du système de mesure de force (ISO 7500-1:2018)

ISO 7500-1:2018 spécifie l'étalonnage et la vérification des machines d'essai de traction/compression.
La vérification consiste en:
- une inspection générale de la machine d'essai, y compris ses accessoires pour l'application des forces;
- un étalonnage du système de mesure de force.
- une confirmation que les propriétés de la machine d'essai concernant ses performances atteignent les limites indiquées pour une classe spécifiée.
NOTE Ce document traite de l'étalonnage et de la vérification statique des systèmes de mesure de force. Les valeurs d'étalonnage ne sont pas nécessairement valables pour les applications d'essais dynamiques ou à grande vitesse. La bibliographie donne des informations complémentaires sur les effets dynamiques.
ATTENTION ? Certains des essais spécifiés dans ce document impliquent l'utilisation de processus qui peuvent conduire à une situation dangereuse.

Kovinski materiali - Umerjanje in preverjanje statičnih enoosnih preskuševalnih strojev - 1. del: Preskuševalni stroji za natezni/tlačni preskus - Umerjanje in preverjanje sistema za merjenje sile (ISO 7500-1:2018)

Ta dokument določa metodo za umerjanje in preverjanje naprav za preskušanje pri nateznih/tlačnih preskusih.
Preverjanje je sestavljeno iz:
– splošnega pregleda naprave za preskušanje, vključno z njegovimi priključki za uvajanje sile;
– umerjanja sistema za merjenje sile naprave za preskušanje;
– potrditve, da zmogljivosti naprave za preskušanje dosegajo mejne vrednosti, podane za določen razred.
OPOMBA: ta dokument obravnava statično umerjanje in preverjanje sistemov za merjenje sile. Ni nujno, da vrednosti umerjanja veljajo za uporabo pri visokih hitrostih ali dinamičnemu preskušanju. Dodatne informacije
o dinamičnih učinkih so podane v bibliografiji.
POZOR – Nekateri preskusi, podani v tem dokumentu, vključujejo uporabo postopkov, ki lahko
vodijo v nevarno stanje.

General Information

Status
Published
Publication Date
13-Mar-2018
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
14-Mar-2018
Completion Date
14-Mar-2018

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SLOVENSKI STANDARD
SIST EN ISO 7500-1:2018
01-julij-2018
1DGRPHãþD
SIST EN ISO 7500-1:2016
.RYLQVNLPDWHULDOL8PHUMDQMHLQSUHYHUMDQMHVWDWLþQLKHQRRVQLKSUHVNXãHYDOQLK
VWURMHYGHO3UHVNXãHYDOQLVWURML]DQDWH]QLWODþQLSUHVNXV8PHUMDQMHLQ
SUHYHUMDQMHVLVWHPD]DPHUMHQMHVLOH ,62

Metallic materials - Calibration and verification of static uniaxial testing machines - Part 1:

Tension/compression testing machines - Calibration and verification of the force-

measuring system (ISO 7500-1:2018)
Metallische Werkstoffe - Kalibrierung und Überprüfung von statischen einachsigen

Prüfmaschinen - Teil 1: Zug- und Druckprüfmaschinen - Kalibrierung und Überprüfung

der Kraftmesseinrichtung (ISO 7500-1:2018)

Matériaux métalliques - Étalonnage et vérification des machines pour essais statiques

uniaxiaux - Partie 1: Machines d'essai de traction/compression - Étalonnage et
vérification du système de mesure de force (ISO 7500-1:2018)
Ta slovenski standard je istoveten z: EN ISO 7500-1:2018
ICS:
77.040.10 Mehansko preskušanje kovin Mechanical testing of metals
SIST EN ISO 7500-1:2018 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN ISO 7500-1:2018
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SIST EN ISO 7500-1:2018
EN ISO 7500-1
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2018
EUROPÄISCHE NORM
ICS 77.040.10 Supersedes EN ISO 7500-1:2015
English Version
Metallic materials - Calibration and verification of static
uniaxial testing machines - Part 1: Tension/compression
testing machines - Calibration and verification of the force-
measuring system (ISO 7500-1:2018)

Matériaux métalliques - Étalonnage et vérification des Metallische Werkstoffe - Kalibrierung und

machines pour essais statiques uniaxiaux - Partie 1: Überprüfung von statischen einachsigen

Machines d'essai de traction/compression - Étalonnage Prüfmaschinen - Teil 1: Zug- und Druckprüfmaschinen

et vérification du système de mesure de force (ISO - Kalibrierung und Überprüfung der

7500-1:2018) Kraftmesseinrichtung (ISO 7500-1:2018)
This European Standard was approved by CEN on 8 March 2018.

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: Rue de la Science 23, B-1040 Brussels

© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7500-1:2018 E

worldwide for CEN national Members.
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SIST EN ISO 7500-1:2018
EN ISO 7500-1:2018 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 7500-1:2018
EN ISO 7500-1:2018 (E)
European foreword

This document (EN ISO 7500-1:2018) has been prepared by Technical Committee ISO/TC 164

“Mechanical testing of metals” in collaboration with Technical Committee ECISS/TC 101 “Test methods

for steel (other than chemical analysis)” 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 2018, and conflicting national standards

shall be withdrawn at the latest by September 2018.

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.

This document supersedes EN ISO 7500-1:2015.

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 7500-1:2018 has been approved by CEN as EN ISO 7500-1:2018 without any

modification.
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SIST EN ISO 7500-1:2018
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SIST EN ISO 7500-1:2018
INTERNATIONAL ISO
STANDARD 7500-1
Fifth edition
2018-02
Metallic materials — Calibration and
verification of static uniaxial testing
machines —
Part 1:
Tension/compression testing machines
— Calibration and verification of the
force-measuring system
Matériaux métalliques — Étalonnage et vérification des machines
pour essais statiques uniaxiaux —
Partie 1: Machines d'essai de traction/compression — Étalonnage et
vérification du système de mesure de force
Reference number
ISO 7500-1:2018(E)
ISO 2018
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SIST EN ISO 7500-1:2018
ISO 7500-1:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved
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SIST EN ISO 7500-1:2018
ISO 7500-1:2018(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols .......................................................................................................................................................................................................................... 2

5 General inspection of the testing machine ................................................................................................................................ 3

6 Calibration of the force-measuring system of the testing machine ................................................................. 3

6.1 General ........................................................................................................................................................................................................... 3

6.2 Determination of the resolution .............................................................................................................................................. 4

6.2.1 Analogue scale ................................................................................................................................................................... 4

6.2.2 Digital scale........................................................................................................................................................................... 4

6.2.3 Variation of readings .................................................................................................................................................... 4

6.2.4 Unit .............................................................................................................................................................................................. 5

6.3 Prior determination of the relative resolution of the force indicator ...................................................... 5

6.4 Calibration procedure ....................................................................................................................................................................... 5

6.4.1 Alignment of the force-proving instrument ............................................................................................. 5

6.4.2 Temperature compensation ................................................................................................................................... 5

6.4.3 Conditioning of the testing machine and force-proving instrument .................................. 6

6.4.4 Procedure ............................................................................................................................................................................... 6

6.4.5 Application of discrete forces ............................................................................................................................... 6

6.4.6 Verification of accessories ....................................................................................................................................... 7

6.4.7 Verification of the effect of differences in piston positions ......................................................... 7

6.4.8 Determination of relative reversibility error .......................................................................................... 7

6.5 Assessment of the force indicator .......................................................................................................................................... 8

6.5.1 Relative indication error ........................................................................................................................................... 8

6.5.2 Relative repeatability error .................................................................................................................................... 9

6.5.3 Agreement between two force-proving instruments ....................................................................... 9

7 Class of testing machine range ............................................................................................................................................................10

8 Verification report ...........................................................................................................................................................................................10

8.1 General information ........................................................................................................................................................................10

8.2 Results of verification ....................................................................................................................................................................11

9 Intervals between verifications .........................................................................................................................................................11

Annex A (normative) General inspection of the testing machine........................................................................................12

Annex B (informative) Inspection of the loading platens of the compression testing machines .......13

Annex C (informative) Uncertainty of the calibration results of the force-measuring system .............14

Bibliography .............................................................................................................................................................................................................................18

© ISO 2018 – All rights reserved iii
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SIST EN ISO 7500-1:2018
ISO 7500-1:2018(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: www .iso .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals,

Subcommittee SC 1, Uniaxial testing.

This fifth edition cancels and replaces the fourth edition (ISO 7500-1:2015), of which it constitutes a

minor revision. The changes compared to the previous edition are as follows:

— the definitions of ΔF, Δm, Δg, E, E′, U, and U′ in Table 1 have been editorially revised.

A list of all parts in the ISO 7500 series can be found on the ISO website.
iv © ISO 2018 – All rights reserved
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SIST EN ISO 7500-1:2018
INTERNATIONAL STANDARD ISO 7500-1:2018(E)
Metallic materials — Calibration and verification of static
uniaxial testing machines —
Part 1:
Tension/compression testing machines — Calibration and
verification of the force-measuring system
1 Scope

This document specifies the calibration and verification of tension/compression testing machines.

The verification consists of:

— a general inspection of the testing machine, including its accessories for the force application;

— a calibration of the force-measuring system of the testing machine;

— a confirmation that the performance properties of the testing machine achieve the limits given for

a specified class.

NOTE This document addresses the static calibration and verification of the force-measuring systems. The

calibration values are not necessarily valid for high-speed or dynamic testing applications. Further information

regarding dynamic effects is given in the Bibliography.

CAUTION — Some of the tests specified in this document involve the use of processes which can

lead to a hazardous situation.
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 376, Metallic materials — Calibration of force-proving instruments used for the verification of uniaxial

testing machines
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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 https:// www .iso .org/ obp
3.1
calibration

operation that establishes the relationship between the force values (with associated uncertainties)

indicated by the testing machine and those measured by one or more force-proving instruments

© ISO 2018 – All rights reserved 1
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SIST EN ISO 7500-1:2018
ISO 7500-1:2018(E)
3.2
verification

confirmation, based on analysis of measurements in accordance with this document, that the

performance properties of the testing machine achieve the limits given for a specified class

4 Symbols
Symbols and their meanings are given in Table 1.
Table 1 — Symbols and their meanings
Symbol Unit Meaning
a % relative resolution of the force indicator of the testing machine
a % relative resolution of the force indicator of the testing machine at the ap-
plied force

a % relative resolution of the force indicator of the testing machine at zero force

b % relative repeatability error of the force-measuring system of the testing ma-

chine
b % allowable value of b for a given class
ΔF N error of the force
Δm kg error of the mass
Δg m/s error of the acceleration due to gravity
E % estimated mean relative error of incremental forces
E′ % estimated mean relative error of decremental forces
f % relative zero error of the force-measuring system of the testing machine
F N reference force indicated by the force-proving instrument with increasing
test force
F′ N reference force indicated by the force-proving instrument with decreasing
test force
F N reference force indicated by the force-proving instrument with increasing
test force, for the complementary series of measurements for the smallest
range used

F N force indicated by the force indicator of the testing machine to be verified,

with increasing test force

F ′ N force indicated by the force indicator of the testing machine to be verified,

with decreasing test force
N arithmetic mean of several measurements of F and F for the same discrete force
FF,

F N force reading on the force indicator of the testing machine to be verified, with

increasing test force, for the complementary series of measurements for the
smallest range used

F N residual indication of the force indicator of the testing machine to be verified

after removal of force
F N maximum value of the calibrated range of the force indicator of the testing
machine
g m/s local acceleration due to gravity
k coverage factor used to calculate the expanded uncertainty from the com-
bined uncertainty
m kg mass of dead weights used to generate a calibration force
q % mean relative indication error of the force-measuring system of the testing
machine
2 © ISO 2018 – All rights reserved
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SIST EN ISO 7500-1:2018
ISO 7500-1:2018(E)
Table 1 (continued)
Symbol Unit Meaning
q % the i measurement of the relative indication error of the force-measuring
system of the testing machine
q % allowable value of q for a given class
q % the maximum value of q at each calibration point
max
q % the minimum value of q at each calibration point
min

q % relative indication error determined at a crossover point using force-proving

instrument 1

q % relative indication error determined at a crossover point using force-proving

instrument 2
r N resolution of the force indicator of the testing machine
u % combined uncertainty
u % uncertainty component
u % uncertainty component due to repeatability
rep
u % uncertainty component due to resolution
res
u % uncertainty component due to the calibration standard used
std
U % expanded uncertainty of incremental forces
U′ % expanded uncertainty of decremental forces
U % expanded uncertainty using force-proving instrument 1 at a crossover point
U % expanded uncertainty using force-proving instrument 2 at a crossover point

v % relative reversibility error of the force-measuring system of the testing machine

ρ kg/m density of air
air
ρ kg/m density of the dead weights
5 General inspection of the testing machine

The calibration of the testing machine shall only be carried out if the machine is in good working order.

For this purpose, a general inspection of the machine shall be carried out before calibration of the force-

measuring system of the machine as indicated in Annex A.

NOTE Good metrological practice requires a calibration run prior to any maintenance or adjustments to the

testing machine to determine the “as found” condition of the machine.

Information on the inspection of the loading platens is provided in Annex B. Uncertainty of the

calibration results is discussed in Annex C.
6 Calibration of the force-measuring system of the testing machine
6.1 General

This calibration shall be carried out for each of the force ranges used and with all force indicators in

use. Any accessory devices (e.g. pointer, recorder) that can affect the force-measuring system shall,

where used, be verified in accordance with 6.4.6.

If the testing machine has several force-measuring systems, each system shall be regarded as a separate

testing machine. The same procedure shall be followed for double-piston hydraulic machines.

The calibration shall be carried out using force-proving instruments with the following exception: if

the force to be verified is below the lower limit of the smallest capacity force-proving device used in the

calibration procedure, use known masses.
© ISO 2018 – All rights reserved 3
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SIST EN ISO 7500-1:2018
ISO 7500-1:2018(E)

When more than one force-proving instrument is required to calibrate a force range, the maximum

force applied to the smaller device shall be the same as the minimum force applied to the next force-

proving instrument of higher capacity. When a set of known masses is used to verify forces, the set shall

be considered as a single force-proving instrument.

The calibration can be carried out with constant indicated forces, F , or the calibration can be carried

out with constant reference forces, F. Calibration can be carried out using a slowly increasing force for

increasing force levels or a slowly decreasing force for decreasing force levels.

NOTE The word “constant” signifies that the same nominal value of F (or F) is used for the three series of

measurements (see 6.4.5).

The instruments used for the calibration shall have a certified traceability to the international system

of units.

The force-proving instrument shall comply with the requirements specified in ISO 376. The class

of the instrument shall be equal to or better than the class for which the testing machine is to be

calibrated. In the case of dead weights, the relative error of the force generated by these weights shall

be within ±0,1 %.

The exact formula giving the force, F, in newtons, created by the dead weight of mass, m, in kilograms,

is given by Formula (1):
 ρ 
air
Fm=−g 1 (1)
 
 
This force can be calculated using Formula (2):
F = mg (2)

The relative error of the force can be calculated from the relative errors of mass and acceleration due to

gravity using Formula (3):
ΔF Δm Δg
= + (3)
F m g
6.2 Determination of the resolution
6.2.1 Analogue scale

The thickness of the graduation marks on the scale shall be uniform and the width of the pointer shall

be approximately equal to the width of a graduation mark.

The resolution, r, of the indicator shall be obtained from the ratio between the width of the pointer and

the centre-to-centre distance between two adjacent scale graduation marks (scale interval), multiplied

by the value of force which one scale interval represents. The recommended ratios are 1:2, 1:5 or 1:10, a

spacing of 2,5 mm or greater being required for the determination of one-tenth of a scale division.

6.2.2 Digital scale

The resolution is taken to be one increment of the count of the numerical indicator.

6.2.3 Variation of readings

If the readings vary by more than the value previously calculated for the resolution (with the force-

proving instrument unloaded and with the motor and/or drive mechanism and control on for

4 © ISO 2018 – All rights reserved
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SIST EN ISO 7500-1:2018
ISO 7500-1:2018(E)

determining the sum of all electrical noise), the resolution, r, shall be deemed to be equal to half the

range of fluctuation plus one increment.

NOTE 1 This only determines the resolution due to system noise and does not account for control errors, e.g.

in the case of hydraulic machines.

NOTE 2 For auto-ranging machines, the resolution of the indicator changes as the resolution or gain of the

system changes.
6.2.4 Unit
The resolution, r, shall be expressed in units of force.
6.3 Prior determination of the relative resolution of the force indicator

The relative resolution, a, of the force indicator is defined by the relationship shown in Formula (4):

a=×100 (4)
where
r is the resolution defined in 6.2;
F is the force indicated by the force indicator of the testing machine.

The relative resolution shall be determined at each calibration point and shall not exceed the values

given in Table 2 for the class of machine being verified.
6.4 Calibration procedure
6.4.1 Alignment of the force-proving instrument

Mount tension force-proving instruments in the machine in such a way as to minimize any effects of

bending (see ISO 376). For the alignment of a force-proving instrument in the compression mode, mount

a platen with a ball nut on the instrument if the machine does not have an incorporated ball cup.

For calibration of tension and compression modes on testing systems that do not use compression

platens for testing, the force-proving device may be attached to the testing machine with threaded

studs. In this case, the force-proving instrument shall have been calibrated in a similar fashion (i.e.

with threaded studs) and rotation of the force-proving instrument through an angle of 120° is required

between each series of measurements during the calibration of the testing machine.

If the machine has two work areas with a common force application and indicating device, one

calibration could be performed, so that, for example, compression in the upper work area equals tension

in the lower work area and vice versa. The certificate should carry an appropriate comment.

6.4.2 Temperature compensation

The calibration shall be carried out at an ambient temperature of between 10 °C and 35 °C. The

temperature at which the calibration is carried out shall be noted in the verification report.

A sufficient period of time shall be provided to allow the force-proving instrument to reach a stable

temperature. The temperature of the force-proving instrument shall not change by more than 2 °C from

the beginning to the end of each calibration run. If necessary, temperature corrections shall be applied

to the readings (see ISO 376).
© ISO 2018 – All rights reserved 5
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SIST EN ISO 7500-1:2018
ISO 7500-1:2018(E)
6.4.3 Conditioning of the testing machine and force-proving instrument

Immediately prior to the calibration procedure, the force-proving instrument, in position in the

machine, shall be preloaded at least three times between zero and the maximum force to be measured.

6.4.4 Procedure
Use either or a combination of the following methods:

a) a nominal force, F , indicated by the force indicator of the machine is applied by the machine and

the reference force, F, indicated by the force-proving instrument is noted;

b) a nominal reference force, F, indicated by the force-proving instrument is applied by the machine

and the force, F , indicated by the force indicator of the machine is noted.

The word nominal implies that it is not necessary to repeat the exact values of force in each series of

measureme
...

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