SIST EN ISO 15530-3:2011

Geometrical product specifications (GPS) - Coordinate measuring machines (CMM): Technique for determining the uncertainty of measurement - Part 3: Use of calibrated workpieces or measurement standards (ISO 15530-3:2011)

This part of ISO 15530 specifies the evaluation of measurement uncertainty for results of measurements obtained by a CMM and by using calibrated workpieces. It provides an experimental technique for simplifying the uncertainty evaluation of CMM measurements, whose approach (substitution measurements) leads to measurements being carried out in the same way as actual measurements, but with calibrated workpieces of similar dimension and geometry instead of the unknown workpieces to be measured. Non-substitution measurements on CMMs are also covered, as are the requirements of the uncertainty evaluation procedure, the measurement equipment needed, and the reverification and the interim check of the measurement uncertainty.
NOTE The evaluation of measurement uncertainty is always related to a specific measuring task.

Geometrische Produktspezifikation und -prüfung (GPS) - Verfahren zur Ermittlung der Messunsicherheit von Koordinatenmessgeräten (KMG) - Teil 3: Anwendung von kalibrierten Werkstücken oder Normalen (ISO 15530-3:2011)

Dieser Teil von ISO 15530 legt die Ermittlung der Messunsicherheit für Ergebnisse von Messungen mit einem
KMG (Koordinatenmessgerät) unter Verwendung kalibrierter Werkstücke fest. Er bietet ein experimentelles
Verfahren zur Vereinfachung der Unsicherheitsermittlung für Messungen mit KMG, dessen Ansatz
(Substitutionsmessungen) dazu führt, dass Messungen in derselben Weise vorgenommen werden wie die
eigentlichen Messungen, aber mit kalibrierten Werkstücken ähnlicher Abmessungen und Form anstelle der
unbekannten zu messenden Werkstücke.
Messungen ohne Substitution auf KMG werden ebenfalls behandelt, sowie auch die Anforderungen des
Verfahrens der Unsicherheitsermittlung, die benötigten Hilfsmittel, die Bestätigungsprüfung und die Zwischenprüfung
der Messunsicherheit.
ANMERKUNG Die Ermittlung der Messunsicherheit bezieht sich immer auf eine bestimmte Messaufgabe.

Spécification géométrique des produits (GPS) - Machines à mesurer tridimensionnelles (MMT): Technique pour la détermination de l'incertitude de mesure - Partie 3: Utilisation de pièces étalonnées ou d'étalons de mesure (ISO 15530-3:2011)

L'ISO 15530-3:2011 spécifie l'évaluation de l'incertitude de mesure des résultats obtenus par une MMT et par l'utilisation de pièces étalonnées ou d'étalons de mesure. Elle fournit une technique expérimentale de simplification de l'évaluation de l'incertitude des mesures réalisées par MMT. Dans cette approche expérimentale (mesures par substitution), les mesures sont réalisées de la même manière que les mesures réelles, mais ce sont des pièces étalonnées ou des étalons de taille et de géométrie similaires qui sont utilisés à la place des objets inconnus à mesurer.
L'ISO 15530-3:2011 couvre également les mesures sans substitution et spécifie les exigences relatives au mode opératoire d'évaluation de l'incertitude, le matériel de mesure nécessaire, la revérification et le contrôle intermédiaire de l'incertitude de mesure.

Specifikacija geometrijskih veličin izdelka - Koordinatni merilni stroji (CMM): postopek ugotavljanja negotovosti meritev - 3. del: Uporaba umerjenih izdelkov ali etalonov (ISO 15530-3:2011)

Ta del ISO 15530 določa vrednotenje meritev negotovosti za rezultate meritev, dobljenih s KMS in uporabo umerjenih izdelkov. Podaja eksperimentalno tehniko za poenostavitev vrednotenja negotovosti meritev KMS, katere pristop (nadomestne meritve) vodi do izvajanja meritev, prav tako kot so bile opravljene dejanske meritve, vendar z umerjenimi izdelki podobnih mer in geometrije, namesto merjenja neznanih izdelkov. Zajete so tudi nenadomestne meritve na KMS in zahteve za postopek vrednotenja negotovosti, potrebna merilna oprema in ponovno overjanje ter vmesno preverjanje negotovosti meritev.
OPOMBA: Vrednotenje negotovosti meritev je vedno povezano s konkretnim merjenjem.

General Information

• Status: Published
• Public Enquiry End Date: 24-Jul-2009
• Publication Date: 08-Nov-2011
• ICS: 17.040.30 - Measuring instruments
• ICS: 17.040.40 - Geometrical Product Specification (GPS)
• Technical Committee: ISEL - Mechanical elements
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 25-Oct-2011
• Due Date: 30-Dec-2011
• Completion Date: 09-Nov-2011
• Ref Project: EN ISO 15530-3:2011 - Geometrical product specifications (GPS) - Coordinate measuring machines (CMM): Technique for determining the uncertainty of measurement - Part 3: Use of calibrated workpieces or measurement standards (ISO 15530-3:2011)

Relations

• Replaces: SIST-TS CEN ISO/TS 15530-3:2008 - Geometrical product specifications (GPS) - Coordinate measuring machines (CMM): Technique for determining the uncertainty of measurement - Part 3: Use of calibrated workpieces or standards (ISO/TS 15530-3:2004)
• Effective Date: 01-Dec-2011

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 15530-3:2011
01-december-2011
1DGRPHãþD
SIST-TS CEN ISO/TS 15530-3:2008
6SHFLILNDFLMDJHRPHWULMVNLKYHOLþLQL]GHOND.RRUGLQDWQLPHULOQLVWURML&00
SRVWRSHNXJRWDYOMDQMDQHJRWRYRVWLPHULWHYGHO8SRUDEDXPHUMHQLKL]GHONRYDOL
HWDORQRY,62
Geometrical product specifications (GPS) - Coordinate measuring machines (CMM):
Technique for determining the uncertainty of measurement - Part 3: Use of calibrated
workpieces or measurement standards (ISO 15530-3:2011)
Geometrische Produktspezifikation und -prüfung (GPS) - Verfahren zur Ermittlung der
Messunsicherheit von Koordinatenmessgeräten (KMG) - Teil 3: Anwendung von
kalibrierten Werkstücken oder Normalen (ISO 15530-3:2011)
Spécification géométrique des produits (GPS) - Machines à mesurer tridimensionnelles
(MMT): Technique pour la détermination de l'incertitude de mesure - Partie 3: Utilisation
de pièces étalonnées ou d'étalons de mesure (ISO 15530-3:2011)
Ta slovenski standard je istoveten z: EN ISO 15530-3:2011
ICS:
17.040.30 Merila Measuring instruments
17.040.40 6SHFLILNDFLMDJHRPHWULMVNLK Geometrical Product
YHOLþLQL]GHOND*36 Specification (GPS)
SIST EN ISO 15530-3:2011 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 15530-3:2011

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SIST EN ISO 15530-3:2011


EUROPEAN STANDARD
EN ISO 15530-3

NORME EUROPÉENNE

EUROPÄISCHE NORM
October 2011
ICS 17.040.30 Supersedes CEN ISO/TS 15530-3:2007
English Version
Geometrical product specifications (GPS) - Coordinate
measuring machines (CMM): Technique for determining the
uncertainty of measurement - Part 3: Use of calibrated
workpieces or measurement standards (ISO 15530-3:2011)
Spécification géométrique des produits (GPS) - Machines à Geometrische Produktspezifikation und -prüfung (GPS) -
mesurer tridimensionnelles (MMT): Technique pour la Verfahren zur Ermittlung der Messunsicherheit von
détermination de l'incertitude de mesure - Partie 3: Koordinatenmessgeräten (KMG) - Teil 3: Anwendung von
Utilisation de pièces étalonnées ou d'étalons de mesure kalibrierten Werkstücken oder Normalen (ISO 15530-
(ISO 15530-3:2011) 3:2011)
This European Standard was approved by CEN on 14 October 2011.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 15530-3:2011: E
worldwide for CEN national Members.

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SIST EN ISO 15530-3:2011
EN ISO 15530-3:2011 (E)
Contents Page
Foreword .3

2

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SIST EN ISO 15530-3:2011
EN ISO 15530-3:2011 (E)
Foreword
This document (EN ISO 15530-3:2011) has been prepared by Technical Committee ISO/TC 213 "Dimensional
and geometrical product specifications and verification" in collaboration with Technical Committee
CEN/TC 290 “Dimensional and geometrical product specification and verification” 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 April 2012, and conflicting national standards shall be withdrawn at the
latest by April 2012.
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 CEN ISO/TS 15530-3:2007.
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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 15530-3:2011 has been approved by CEN as a EN ISO 15530-3:2011 without any
modification.

3

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SIST EN ISO 15530-3:2011

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SIST EN ISO 15530-3:2011

INTERNATIONAL ISO
STANDARD 15530-3
First edition
2011-10-15


Geometrical product specifications
(GPS) — Coordinate measuring machines
(CMM): Technique for determining the
uncertainty of measurement —
Part 3:
Use of calibrated workpieces or
measurement standards
Spécification géométrique des produits (GPS) — Machines à mesurer
tridimensionnelles (MMT): Technique pour la détermination de
l'incertitude de mesure —
Partie 3: Utilisation de pièces étalonnées ou d'étalons de mesure




Reference number
ISO 15530-3:2011(E)
©
ISO 2011

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SIST EN ISO 15530-3:2011
ISO 15530-3:2011(E)

COPYRIGHT PROTECTED DOCUMENT


©  ISO 2011
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56  CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland

ii © ISO 2011 – All rights reserved

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SIST EN ISO 15530-3:2011
ISO 15530-3:2011(E)
Contents Page
Foreword . iv
Introduction . v
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 1
4  Symbols . 2
5  Requirements . 3
5.1  Operating conditions . 3
5.2  Similarity conditions . 3
6  Principle of the uncertainty evaluation using calibrated workpieces . 4
7  Procedure . 4
7.1  Measuring equipment . 4
7.2  Execution . 4
7.3  Calculation of the uncertainty . 5
7.4  Applying the substitution method: special considerations . 9
8  Reverification of the measurement uncertainty . 9
9  Interim check of the measurement uncertainty . 10
Annex A (informative) Examples of application. 11
Annex B (informative) Relation to the GPS matrix model . 16
Bibliography . 18

© ISO 2011 – All rights reserved iii

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SIST EN ISO 15530-3:2011
ISO 15530-3:2011(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 15530-3 was prepared by Technical Committee ISO/TC 213, Dimensional and geometrical product
specifications and verification.
This first edition of ISO 15530-3 cancels and replaces ISO/TS 15530-3:2004, which has been technically
revised.
ISO 15530 consists of the following parts, under the general title Geometrical product specifications (GPS) —
Coordinate measuring machines (CMM): Technique for determining the uncertainty of measurement:
 Part 1: Overview and metrological characteristics [Technical Specification]
 Part 3: Use of calibrated workpieces or measurement standards
 Part 4: Evaluating task-specific measurement uncertainty using simulation [Technical Specification]

iv © ISO 2011 – All rights reserved

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SIST EN ISO 15530-3:2011
ISO 15530-3:2011(E)
Introduction
This part of ISO 15530 is a Geometrical Product Specification (GPS) and is to be regarded as a general GPS
document (see ISO/TR 14638). It influences chain link 6 of the chain of standards on size, distance, radius,
angle, form, orientation, location, run-out and datums.
The ISO/GPS Masterplan given in ISO/TR 14638 gives an overview of the ISO/GPS system of which this
standard is a part. The fundamental rules of ISO/GPS given in ISO 8015 apply to this document and the
default decision rules given in ISO 14253-1 apply to specifications made in accordance with this document,
unless otherwise indicated.
For more detailed information on the relation of this standard to the GPS matrix model, see Annex B.
Coordinate measuring machines (CMMs) have become essential for the verification of geometry in industry.
According to the ISO 9000 series of standards, in a quality management system, the relevant measuring
equipment is required to be calibrated against certified equipment having a known and valid relationship to
internationally or nationally recognized standards in order to establish traceability. According to the
International vocabulary of basic and general terms in metrology (VIM), a calibration comprises — besides the
establishment of the relationship between the measured and the correct values of a quantity — the uncertainty
evaluation in the final results (measurands) of the measurement task. However, uncertainty evaluation
methods covering the errors arising in the innumerable measurement tasks a CMM can actually perform are
often very complex. In these cases, the risk of an unrealistic estimation of task-related uncertainty is likely to
arise.
The aim of this part of ISO 15530 is to provide an experimental technique for simplifying the uncertainty
evaluation of CMM measurements. In this experimental approach, measurements are carried out in the same
way as actual measurements, but with calibrated workpieces or measurement standards of similar dimension
and geometry instead of the unknown objects to be measured. The description of this experimental technique
to evaluate measurement uncertainty is the key element of this part of ISO 15530. The standardization of such
procedures for the uncertainty evaluation serves the worldwide mutual recognition of calibrations and other
measurement results.
This part of ISO 15530 is applicable for non-substitution measurement of workpieces or measurement
standards, where the measurement result is given by the indication of the CMM. Furthermore, this part of
ISO 15530 is applicable for substitution measurement, where, in opposition to the non-substitution
measurement, a check standard is used to correct for the systematic errors of the CMM. The latter will
generally decrease the measurement uncertainty and is often used, especially in the field of gauge calibration.
This part of ISO 15530 describes one of several methods of uncertainty evaluation, which will be outlined in
later ISO documents. Because of the experimental approach, it is simple to perform, and it provides realistic
statements of measurement uncertainties.
The limitations of this method can be summarized as: the availability of artefacts with sufficiently defined
geometrical characteristics, stability, reasonable costs, and the possibility of being calibrated with sufficiently
small uncertainty.

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SIST EN ISO 15530-3:2011

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SIST EN ISO 15530-3:2011
INTERNATIONAL STANDARD ISO 15530-3:2011(E)

Geometrical product specifications (GPS) — Coordinate
measuring machines (CMM): Technique for determining the
uncertainty of measurement —
Part 3:
Use of calibrated workpieces or measurement standards
1 Scope
This part of ISO 15530 specifies the evaluation of measurement uncertainty for results of measurements
obtained by a CMM (coordinate measuring machine) and by using calibrated workpieces or measurement
standards. It provides an experimental technique for simplifying the uncertainty evaluation of CMM
measurements, whose approach (substitution measurements) leads to measurements being carried out in the
same way as actual measurements, but with calibrated workpieces of similar dimension and geometry instead
of the unknown workpieces to be measured.
Non-substitution measurements on CMMs are also covered, as are the requirements of the uncertainty
evaluation procedure, the measurement equipment needed, and the reverification and interim check of the
measurement uncertainty.
NOTE The evaluation of measurement uncertainty is always related to a specific measuring task.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 10360-1:2000, Geometrical Product Specifications (GPS) — Acceptance and reverification tests for
coordinate measuring machines (CMM) — Part 1: Vocabulary
ISO/IEC Guide 98-3:2008, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
ISO/IEC Guide 99:2007, International vocabulary of metrology — Basic and general concepts and associated
terms (VIM)
ISO 14978:2006, Geometrical product specification (GPS) — General concepts and requirements for GPS
measuring equipment
3 Terms and definitions
For the purpose of this part of ISO 15530, the terms and definitions given in ISO 10360-1, ISO/IEC Guide 98-3,
ISO/IEC Guide 99 and the following apply.
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SIST EN ISO 15530-3:2011
ISO 15530-3:2011(E)
3.1
non-substitution measurement
measurement where the uncorrected indication of the CMM is used as a result
3.2
substitution measurement
measurement where both a workpiece and a check standard are measured in order to provide additional
corrections for systematic errors of the CMM
4 Symbols
For the purpose of this part of ISO 15530, the symbols given in Table 1 apply.
Table 1 — Symbols
Symbol Interpretation
b Systematic error observed during the evaluation of the measurement uncertainty
Difference between the measured and calibrated values of the check standard when applying the

i
substitution method
k Coverage factor
l Measured dimension
n Number of repeated measurements
T Average temperature of the workpiece or measurement standard
u Standard uncertainty of the parameter of the calibrated workpiece or measurement standard
cal
u Standard uncertainty of the measurement procedure
p
u Standard uncertainty of the systematic error
b
u Standard uncertainty associated with the variations in the uncalibrated workpieces
w
Standard uncertainty associated with the variations in the mechanical properties of the uncalibrated
u
wp
workpieces
Standard uncertainty associated with the variations in the CTEs (thermal expansion coefficients) of the
u
wt
uncalibrated workpieces
u Standard uncertainty of the thermal expansion coefficient

U Expanded measurement uncertainty
U Expanded uncertainty of the calibrated workpiece parameter or measurement standard
cal
x Value of the parameter of the calibrated workpiece or measurement standard
cal
y Measurement result
y Measurement results during evaluation of measurement uncertainty
i
Uncorrected indications of the CMM during evaluation of measurement uncertainty when applying the
*
y
i
substitution method
y Mean value of the measurement result
2 © ISO 2011 – All rights reserved

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SIST EN ISO 15530-3:2011
ISO 15530-3:2011(E)
5 Requirements
5.1 Operating conditions
Before starting the measurements, initialize the CMM and perform procedures such as probe configuration
and probe qualification according to the conditions specified in the manufacturer's operating manual. In
particular, an adequate thermal equilibrium of the (calibrated) workpiece or measurement standard and the
CMM should exist.
For the measurements given in 7.2, the environmental and operational conditions quoted by the CMM
manufacturer and conditions quoted in the user's quality manual shall apply. In particular, existing error
compensating functions (such as corrections applied via the software of the CMM's computer) shall be active
if this is prescribed in the quality manual.
The CMM shall fulfil the specifications of the manufacturer, or — if different — the specifications laid down in
the procedural instructions for the measurement task (task-related calibration, see ISO 14978); therefore, it is
not necessary to calibrate all the metrological characteristics of a CMM (global calibration, see ISO 14978).
5.2 Similarity conditions
The method requires similarity of the following.
a) The dimension and geometry of the workpiece or measurement standard used in the actual
measurements (see 7.2.2) and the calibrated workpiece or measurement standard used in the evaluation
of measurement uncertainty (see 7.2.3).
NOTE   Conditions to be repeated are, for example, positions and orientations.
b) The measurement procedure of the evaluation of measurement uncertainty and the actual measurement.
NOTE   Conditions to be repeated are, for example, handling, exchange and clamping, time elapsed between
probing points, loading and unloading procedures, measuring force and speed.
c) The environmental conditions (including all variations) during evaluation of measurement uncertainty and
actual measurement.
NOTE   Conditions to be repeated are, for example, temperature, temperature stabilization time and temperature
corrections (if used).
In Table 2, the similarity requirements are given.
Table 2 — Similarity requirements for workpieces or standard to be measured and
the calibrated workpieces or standard used during evaluation of measurement uncertainty
Subject Requirements
Identical within:
Dimensions  10 % beyond 250 mm
Dimensional characteristics
 25 mm below 250 mm
Angles Identical within 5°
Form error and surface texture Similar due to functional properties
Material (e.g. thermal expansion, elasticity, hardness) Similar due to functional properties
Measuring strategy Identical
Probe configuration Identical
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SIST EN ISO 15530-3:2011
ISO 15530-3:2011(E)
The similarity of the thermal conditions are considered to be assured if the above requirements are met. The
evaluation of measurement uncertainty using the calibrated workpiece shall cover, in particular, the range of
temperatures which will prevail during the measurements of the uncalibrated workpieces. If the variation of the
thermal expansion coefficient of the measured workpieces or standards is assumed to be significant, this
uncertainty contribution has to be taken into account (see 7.3.3 and 7.3.4).
For some CMMs, errors associated with dynamic effects may become significant with a decreasing probe
approach distance. For small internal features, e.g. a hole, the probe approach distance may be limited by the
feature size. Consequently, care shall be taken to ensure that the probe approach distance is identical.
6 Principle of the uncertainty evaluation using calibrated workpieces
The evaluation of measurement uncertainty is a sequence of measurements, performed in the same way and
under the same conditions as the actual measurements. The only difference is that, instead of the workpieces
to be measured, one or more calibrated workpieces are measured. The differences between the results
obtained by the measurement and the known calibration values of these calibrated workpieces are used to
estimate the uncertainty of the measurements.
The uncertainty of the measurement consists of uncertainty contributions
a) due to the measurement procedure,
b) from the calibration of the calibrated workpiece,
c) due to the variations of the measured workpieces (changing form deviations, expansion coefficient and
surface texture).
The full effect of all variation in environmental conditions should be included to perform a comprehensive
evaluation of the measurement uncertainty.
7 Procedure
7.1 Measuring equipment
The uncertainty evaluation on a CMM using calibrated workpieces requires the following equipment:
a) a task-related stylus set-up;
b) at least one calibrated workpiece.
The metrological characteristics of the calibrated workpieces shall be calibrated with a known and sufficiently
low uncertainty to fulfil the requirements of the measurement task.
The probe shall be re-qualified for each calibration.
The uncertainty stated for the calibration of the calibrated workpieces should be valid for the measurement
strategy employed during the actual measurements and the uncertainty evaluation, i.e. the measurand of the
calibrated workpiece shall be the same as the measurand evaluated in the measurement uncertainty process.
7.2 Execution
7.2.1 General
The user of the CMM has a high degree of freedom to design the measurement procedure (i.e. the
measurement strategy) according to the technical requirements. This is possible because the procedure and
conditions of actual measurements and those during the uncertainty evaluation shall be the same.
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SIST EN ISO 15530-3:2011
ISO 15530-3:2011(E)
7.2.2 Actual measurement
One cycle of an actual measurement consists of the handling of the workpieces and one or more
measurements of the workpieces (see Figure 1).

Figure 1 — Procedure of non-substitution measurement — Measurement cycle
The position and the orientation of the measured workpieces are free within the range covered by the
uncertainty evaluation.
7.2.3 Uncertainty evaluation
The uncertainty evaluation shall be as follows.
Calibrated workpieces are measured instead of the workpieces. Calibrated workpieces and workpieces shall
fulfil the similarity conditions outlined in 5.2. Special loading and unloading procedures shall be performed
during the uncertainty evaluation.
To obtain a sufficient number of samples for the uncertainty evaluation, at least 10 measurement cycles and a
total of at least 20 measurements on calibrated workpieces shall be carried out. For example, a total of
20 cycles is the minimum, if only one calibrated workpiece per cycle is measured.
During the uncertainty evaluation, the position and orientation of the calibrated workpieces are systematically
varied within the limits given by the procedure of the actual measurements.
As specified in 7.2.2, a measurement cycle shall contain all actions involved in a real measurement to ensure
the similarity of thermal conditions. This implies, for example, that the CMM has to move through the same
positions as if a complete measurement were being carried out, even though during the uncertainty evaluation
not all workpieces might be present (dummy measurements).
7.3 Calculation of the uncertainty
7.3.1 General
In a calibration certificate or measurement report, the measurement result, y, and its expanded uncertainty, U,
shall be expressed in the form y  U, where U is determined with a coverage factor k  2 for an approximated
coverage probability of 95 %.
When performing the measurements, four uncertainty contributions shall basically be taken into account,
described by the following standard uncertainties:
u standard uncertainty associated with the uncertainty of the calibration of the calibrated workpiece

cal
stated in the calibration certificate;
u standard uncertainty associated with the measurement procedure as assessed below;

p
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SIST EN ISO 15530-3:2011
ISO 15530-3:2011(E)
u standard uncertainty associated with the systematic error of the measurement process evaluated

b
using the calibrated workpiece;
u standard uncertainty associated with material and manufacturing variations (due to the variation of

w
expansion coefficient, form errors, roughness, elasticity and plasticity).
The expanded measuring uncertainty, U, of any measured parameter is calculated from these standard
uncertainties as:
2 222
Uk u uuu 
cal p b w
The coverage factor, k, is recommended to be chosen as k  2 for a coverage probability of 95 %.
In Table 3, the uncertainty contributions for the measurement are listed.
Table 3 — Uncertainty components and their consideration in the uncertainty assessment
Method of evaluation
Uncertainty component Designation
a
(according to the GUM )
Geometrical errors of CMM
Temperature of CMM
Drift of CMM
Temperature of workpiece
Systematic errors of probing system
Repeatability of the CMM
Assessed in a sum
Scale resolution of the CMM A
u
p
Temperature gradients of the CMM
Random errors of the probing system
Probe changing uncertainty
Errors induced by the procedure (clamping, handling, etc.)
Errors induced by dirt
Errors induced by the measuring strategy
Calibration uncertainty of the calibrated workpiece B u
cal
All the factors contributing to u and the thermal environment
p
B u
b
during the assessment of the calibrated work
...