ISO 18653:2003

Gears - Evaluation of instruments for the measurement of individual gears

ISO 18653:2003 specifies methods for the evaluation of measuring instruments used for gear measurements of involute, helix, pitch and runout. It is applicable both to instruments that measure runout directly and to those that compute it from index measurements. It also gives recommendations for the evaluation of tooth thickness measuring instruments and, of necessity, includes the estimation of measurement uncertainty with the use of calibrated gear artifacts. It does not address the calibration of artifacts by laboratories accredited in accordance with ISO 17025; nor are its requirements intended as an acceptance specification of product gears (see ISO 1328-1, ISO 1328-2, ISO/TR 10064-1 and ISO/TR 10064-2). The estimation of product gear measurement uncertainty is beyond its scope (see ISO/TR 10064-5 for recommendations).

Engrenages — Évaluation des instruments de mesure des engrenages individuels

L'ISO 18653:2003 spécifie des méthodes d'évaluation des instruments utilisés pour mesurer la développante de cercle, l'hélice, le pas et le faux-rond de rotation des engrenages. Elle est applicable aussi bien aux instruments qui mesurent le faux-rond directement qu'à ceux qui le calculent à partir de mesures de divisions. L'ISO 18653:2003 donne également des recommandations sur l'évaluation des instruments de mesure de l'épaisseur des dents et, nécessairement, elle inclut une estimation de l'incertitude de mesure à l'aide d'artefacts d'engrenages calibrés. Elle ne traite cependant pas de l'étalonnage des artefacts par des laboratoires accrédités conformément à l'ISO 17025, et ses exigences ne sont pas destinées à servir de base à l'acceptation des engrenages fabriqués (voir l'ISO1328-1, l'ISO1328-2, l'ISO/TR 10064-1 et l'ISO/TR 10064-2). L'estimation de l'incertitude de mesure des engrenages fabriqués n'entre pas dans son domaine d'application (voir pour cela l'ISO/TR 10064-5).

Zobniki - Vrednotenje instrumentov za merjenje posameznih zobnikov

General Information

• Status: Published
• Publication Date: 19-Nov-2003
• ICS: 21.200 - Gears
• Technical Committee: ISO/TC 60 - Gears
• Drafting Committee: ISO/TC 60/WG 2 - Accuracy of gears
• Current Stage: 9092 - International Standard to be revised
• Start Date: 10-Nov-2025
• Completion Date: 27-Dec-2025
• Ref Project: SIST ISO 18653:2005 - Gears -- Evaluation of instruments for the measurement of individual gears

Overview

ISO 18653:2003 - Gears: Evaluation of instruments for the measurement of individual gears - specifies methods to evaluate gear-measuring instruments used to measure involute profile, helix (lead), pitch and runout. It applies to instruments that measure runout directly and to instruments that compute runout from indexed measurements. The standard also gives recommendations for tooth thickness measurement and requires estimation of measurement uncertainty using calibrated gear artifacts. ISO 18653:2003 is an instrument-evaluation standard; it does not define acceptance criteria for product gears nor does it replace artifact calibration by accredited laboratories (ISO/IEC 17025).

Key topics and requirements

• Scope of measurement: involute, helix, pitch, runout and tooth thickness on individual gears.
• Artifacts: requirements for calibrated artifacts (size, geometry, involute/helix forms, pitch/runout features and workpiece-like artifacts) to transfer traceability and evaluate instrument performance.
• Traceability: unbroken calibration chain from primary laboratories to shop-floor instruments using calibrated gear artifacts; the hierarchy of calibration is emphasized.
• Measurement uncertainty: procedures and methods (including comparator approaches) to estimate uncertainty for the measurement process; guidance that conventional practice aims for measurement uncertainty < 10% of tolerance where feasible (with a note that for very high-accuracy gears this may be technically unattainable).
• Sources of uncertainty: artifact data and calibration, repeatability, reproducibility, probe dynamics (filtering/damping), environmental influences (temperature, vibration), mechanical alignment, runout/mounting errors, servo control and evaluation software, and operator effects.
• Measurement-system condition: checks for system alignment, suitability for calibration, table load effects, tooling/gauges and recommended evaluation intervals.
• Documentation: artifact calibration certificate requirements (see Annex A) and recommendations for interim checks on designated artifacts.

Practical applications and users

ISO 18653 is intended for:

• Gear manufacturers and suppliers validating on-line or shop-floor gear-measuring instruments.
• Metrology and quality engineers establishing measurement uncertainty and traceability for gear inspection.
• Instrument manufacturers and service providers performing acceptance tests, interim checks and performance verification.
• Calibration laboratories and QA teams using calibrated gear artifacts to assess instrument performance (note: calibration of artifacts by accredited labs is outside this standard).

Use cases include acceptance testing of new gear measurement machines, periodic verification of measurement processes, and preparation of documented measurement uncertainty for internal quality control.

Related standards

• ISO 1328-1, ISO 1328-2 (gear accuracy and deviations)
• ISO/TR 10064-1, ISO/TR 10064-2, ISO/TR 10064-5 (gear inspection practice and instrument evaluation)
• ISO/IEC 17025 (laboratory accreditation - calibration practices)
• ISO 14253-1 and ISO/TS 14253-2 (inspection by measurement and decision rules)

Keywords: ISO 18653:2003, gear measurement, gear-measuring instruments, measurement uncertainty, calibrated gear artifacts, runout, involute, helix, pitch, tooth thickness, traceability.

Standards Content (Sample)

SLOVENSKI STANDARD
01-januar-2005
Zobniki - Vrednotenje instrumentov za merjenje posameznih zobnikov
Gears -- Evaluation of instruments for the measurement of individual gears
Engrenages -- Évaluation des instruments de mesure des engrenages individuels
Ta slovenski standard je istoveten z: ISO 18653:2003
ICS:
21.200 Gonila Gears
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 18653
First edition
2003-12-01
Gears — Evaluation of instruments for
the measurement of individual gears
Engrenages — Évaluation des instruments de mesure des engrenages
individuels
Reference number
©
ISO 2003
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2003
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 2003 — All rights reserved

Contents Page
Foreword. iv
1 Scope. 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
4 Application. 4
4.1 General. 4
4.2 Traceability . 4
4.3 Artifacts. 4
4.4 Measurement uncertainty. 5
4.5 Sources of uncertainty . 5
4.6 Evaluation interval . 6
5 Condition of the measurement system. 6
5.1 System characteristics. 6
5.2 Suitability for calibration. 6
5.3 Table load considerations. 6
5.4 Tooling and gauges . 6
6 Environment . 7
7 Artifacts. 7
7.1 Artifact size and geometry . 7
7.2 Involute artifacts . 8
7.3 Helix artifacts. 9
7.4 Pitch artifacts . 10
7.5 Runout artifacts. 11
7.6 Tooth thickness artifacts. 11
7.7 Workpiece-like artifacts. 13
8 Method for estimating measurement uncertainty . 13
8.1 Methods. 14
8.2 Comparator method. 14
8.3 Calculation of U measurement uncertainty . 14
8.4 Procedure. 15
Annex A (normative) Artifact calibration certificate requirements . 17
Bibliography . 19

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 18653 was prepared by Technical Committee ISO/TC 60, Gears.

iv © ISO 2003 — All rights reserved

INTERNATIONAL STANDARD ISO 18653:2003(E)

Gears — Evaluation of instruments for the measurement of
individual gears
1 Scope
This International Standard specifies methods for the evaluation of measuring instruments used for gear
measurements of involute, helix, pitch and runout. It is applicable both to instruments that measure runout
directly and to those that compute it from index measurements. It also gives recommendations for the
evaluation of tooth thickness measuring instruments and, of necessity, includes the estimation of
measurement uncertainty with the use of calibrated gear artifacts. It does not address the calibration of
artifacts by laboratories accredited in accordance with ISO/IEC 17025; nor are its requirements intended as an
acceptance specification of product gears (see ISO 1328-1, ISO 1328-2, ISO/TR 10064-1 and
ISO/TR 10064-2). The estimation of product gear measurement uncertainty is beyond its scope (see
ISO/TR 10064-5 for recommendations).
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 1328-1, Cylindrical gears — ISO system of accuracy — Part 1: Definitions and allowable values of
deviations relevant to corresponding flanks of gear teeth
ISO/TR 10064-3, Cylindrical gears — Code of inspection practice — Part 3: Recommendations relative to
gear blanks, shaft centre distance and parallelism of axes
1)
ISO/TR 10064-5 , Cylindrical gears — Code of inspection practice — Part 5: Recommendations relative to
evaluation of gear measuring instruments
ISO 14253-1, Geometrical Product Specifications (GPS) — Inspection by measurement of workpieces and
measuring equipment — Part 1: Decision rules for proving conformance or non-conformance with
specifications
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
3 Terms, definitions and symbols
For the purposes of this document, the following terms, definitions and symbols (see Table 1) apply.
NOTE 1 The definitions, when applicable, conform to ISO 122-1, ISO 1328-1, ISO 1328-2 and ISO/TR 10064-1.
NOTE 2 The terms, definitions and symbols used in this document may differ from those used in other International
Standards. The user needs to be certain of fully understanding them, as used here.

1) Under preparation.
3.1
accuracy
closeness of agreement between a measured value and an accepted reference (or calibrated) value
3.2
artifact
object of specific shape used to determine the accuracy of measuring devices
See Clause 7.
3.3
bias
difference between the observed average of measurements and the calibration value
See Figure 1.
NOTE Bias can be affected by systematic errors such as linearity or gain and can be different throughout the
operating range of the measurement system.

Key
1 calibration value
2 observed average
3 bias
Figure 1 — Bias
3.4
calibration
set of operations that establish, under specified conditions, the relationship between values of quantities
indicated by a measuring instrument or measuring system and the corresponding values realized by
standards
3.5
gain
magnification factor between the input and the output
3.6
helix artifact
artifact having a calibrated helix form
3.7
involute artifact
calibrated artifact having an involute form determined by a specific base circle
2 © ISO 2003 — All rights reserved

3.8
measurand
particular quantity subject to measurement
3.9
pitch and runout artifact
artifact with calibrated index features for pitch or runout or both
3.10
repeatability (of measurement results)
closeness of the agreement between results of successive measurements of the same measurand carried out
under the same conditions of measurement
3.11
reproducibility (of measurement results)
closeness of the agreement between results of measurements of the same measurand carried out under
changed conditions of measurement
NOTE 1 A valid statement of reproducibility requires specification of the conditions changed.
NOTE 2 The changed conditions may include
 principle of measurement,
 method of measurement,
 observer,
 measuring instrument,
 reference standard,
 location,
 conditions of use, and
 time.
NOTE 3 Reproducibility may be expressed quantitatively in terms of dispersion characteristics of the results.
3.12
uncertainty (of measurement results)
parameter associated with the result of a measurement that characterizes the dispersion of the values that
could be reasonably attributed to the measurand
NOTE 1 The parameter can be, for example, a standard deviation (or a given multiple of it), or the half-width of an
interval having a stated level of confidence.
NOTE 2 Uncertainty of measurement comprises, in general, many components. Some of these components can be
evaluated from the statistical distribution of the results of a series of measurements and can be characterized by
experimental standard deviations. The other components, which also can be characterized by standard deviations, are
evaluated from assumed probability distributions based on experience or other information.
NOTE 3 It is understood that the result of the measurement is the best estimate of the value of the measurand, and
that all components of uncertainty, including those arising from systematic effects, such as components associated with
corrections and reference standards, contribute to the dispersion.
Table 1 — Symbols
Symbol Definition Unit Where first
used
E Bias µm Eq. 1
k Coverage factor — Eq. 1
n Number of measurements — Eq. 2
U Measuring uncertainty µm Eq. 1

U Uncertainty estimation µm Eq. 4

95c
U Measurement uncertainty stated in reference artifact calibration document µm Eq. 3

95(cal)
u Standard uncertainty µm Eq. 1

m
u Reference artifact calibration uncertainty µm Eq. 1
n
u Geometry similarity influence µm Eq. 1

g
u Workpiece characteristic influence µm Eq. 1

w
X Individual measured value of parameter calibrated µm Eq. 2

i
X Mean of measured values µm Eq. 2

4 Application
4.1 General
The purpose of the tests prescribed in this standard is to estimate measurement uncertainty. It has been
assumed that the gear-measuring instrument has been installed on site and a series of acceptance tests have
been completed successfully. Prescribed tests may serve as interim checks to verify the measurement
process.
The measurement and evaluation procedures may be used as part of acceptance tests for a new gear-
measuring instrument, with prior agreement between customer and supplier. In this situation it is
recommended that a series of traceably calibrated gear artifacts be used to verify the measurement
uncertainty at specific points throughout the working volume of the instrument. These measurements should
include provision for testing the machine with table loads that represent the weight of product gears being
tested.
4.2 Traceability
The term traceability implies an unbroken calibration chain from measurements taken on shop floor inspection
instruments to the primary artifacts at a national laboratory, see Figure 2. Traceability is transferred by
calibrated gear artifacts. The primary laboratory has the lowest uncertainty, and uncertainty increases at each
level as the traceability chain is transferred to shop floor measuring instruments. Minimizing the steps from the
primary laboratory to a shop floor measuring instrument will reduce the measurement uncertainty.
4.3 Artifacts
The gear artifacts used for these tests shall be of similar size and geometry to product gears inspected on the
measuring instrument. Artifacts shall be used to evaluate the accuracy of each parameter inspected: helix
(lead), profile, pitch, runout and tooth thickness. Specific artifact requirements are given in Clause 7.
4 © ISO 2003 — All rights reserved

4.4 Measurement uncertainty
Conventional practice recommends the uncertainty of a measurement process be less than 10 % of the
parameter tolerance measured, to ensure that the reliable interpretation of the measurement results is
possible. However, this is not technically achievable when inspecting high accuracy gears.
For example, in gears with tolerances better than 10 µm, the best achievable uncertainty may be only 20 to
30 %. To determine the uncertainty, see Clause 8 and ISO/TR 10064-5. Recommendations for allowable
measurement uncertainty are made in ISO/TR 10064-5.

Figure 2 — Hierarchy of calibration
4.5 Sources of uncertainty
The verification of measurement uncertainty shall include, but not be limited to, the assessment of the
principal contributions to uncertainty in gear measurement as follows:
 artifact data;
 calibration data;
 repeatability of the instrument;
 reproducibility of the instrument;
 probe system filtering, damping and dynamic response, and accuracy;
 environmental influence, including temperature, vibration;
 mechanical alignment;
 runout and mounting error measurement;
 servo control system;
 evaluation software;
 operator.
Refer to ISO/TS 14253-2 for further information on this subject.
4.6 Evaluation interval
The user shall establish the interval for evaluation of the measurement process. It is also recommended that
interim tests be performed on a designated artifact. Data produced by the interim tests on calibrated gear
artifacts can be used for measurement uncertainty.
5 Condition of the measurement system
5.1 System characteristics
Several characteristics of the measuring instrument and readout system should be checked or verified before
proceeding with artifact measurement.
5.2 Suitability for calibration
The instrument should be suitable for calibration and representative of the normal operating conditions.
5.2.1 Instrument alignment
When the instrument manufacturer provides procedural checks for verification of alignments, these checks
shall be made on a regular basis. Instrument alignment includes such things as runout of centres, whether the
centres are coaxial, parallelism of centre axis to instrument ways, squareness of ways, etc. See
ISO/TR 10064-5.
5.2.2 Readout condition
Meter movements and chart recorders should be checked to the manufacturer’s specifications such as
magnification, linearity, lost motion, and frequency response. See ISO/TR 10064-5.
5.3 Table load considerations
Instruments that are used to check very large gears (above 1 m) may deflect or change shape under the
weight of the part being tested. This will cause deviations in measurement. Such instruments should be
calibrated with a simulated load on the table. Gears with significant inertial mass can also cause measurement
deviations. The effects of driving methods such as centre size, friction characteristics, live or dead centres, etc.
should be considered.
5.4 Tooling and gauges
Any tooling or gauges used in the set up or calibration of a measuring instrument shall be calibrated at
suitable intervals.
6 © ISO 2003 — All rights reserved

6 Environment
The stability of the environment will affect accuracy of the calibration process and measurement of production
parts. The required environment specified by the instrument manufacturer shall be met during its evaluation
and use. Calibration requires an environment controlled to the extent necessary to assure continued
measurements of required accuracy considering temperature, humidity, vibration, cleanliness and other
controllable factors affecting precision measurement.
In particular, an adequate thermal equilibrium of the reference artifact and the instrument should exist. If
measurements of the reference artifact are taken with an ambient temperature other than that of its calibration
(normally 20 °C), either the calibrated value shall be adjusted to the actual operating temperature or the
measured values shall be corrected to the calibration temperature. This procedure will add significant sources
of uncertainty to the calibration process. See ISO/TR 10064-5 for details.
7 Artifacts
7.1 Artifact size and geometry
This clause describes artifacts for estimating measurement uncertainty. Artifacts are required for verifying
every parameter measured by an instrument, namely helix (lead), involute, pitch, runout and tooth thickness.
Artifacts may be work-piece-like, such as an accurate gear.
The specific requirements are prescribed in the following sections. Further recommendations, supporting
information and artifact design details are presented in ISO/TR 10064-5.
The minimum requirement is that the artifact size shall be selected as near as practical to the centre of the
measurement range over which the instrument is used.
Ideally, the geometry of the artifacts should represent the tooth number, module, helix angle, facewidth and
weight of the product gear range. The artifacts should have left and right flank features. Single flank artifacts
may be used inverted to simula
...

INTERNATIONAL ISO
STANDARD 18653
First edition
2003-12-01
Gears — Evaluation of instruments for
the measurement of individual gears
Engrenages — Évaluation des instruments de mesure des engrenages
individuels
Reference number
©
ISO 2003
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2003
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 2003 — All rights reserved

Contents Page
Foreword. iv
1 Scope. 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
4 Application. 4
4.1 General. 4
4.2 Traceability . 4
4.3 Artifacts. 4
4.4 Measurement uncertainty. 5
4.5 Sources of uncertainty . 5
4.6 Evaluation interval . 6
5 Condition of the measurement system. 6
5.1 System characteristics. 6
5.2 Suitability for calibration. 6
5.3 Table load considerations. 6
5.4 Tooling and gauges . 6
6 Environment . 7
7 Artifacts. 7
7.1 Artifact size and geometry . 7
7.2 Involute artifacts . 8
7.3 Helix artifacts. 9
7.4 Pitch artifacts . 10
7.5 Runout artifacts. 11
7.6 Tooth thickness artifacts. 11
7.7 Workpiece-like artifacts. 13
8 Method for estimating measurement uncertainty . 13
8.1 Methods. 14
8.2 Comparator method. 14
8.3 Calculation of U measurement uncertainty . 14
8.4 Procedure. 15
Annex A (normative) Artifact calibration certificate requirements . 17
Bibliography . 19

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 18653 was prepared by Technical Committee ISO/TC 60, Gears.

iv © ISO 2003 — All rights reserved

INTERNATIONAL STANDARD ISO 18653:2003(E)

Gears — Evaluation of instruments for the measurement of
individual gears
1 Scope
This International Standard specifies methods for the evaluation of measuring instruments used for gear
measurements of involute, helix, pitch and runout. It is applicable both to instruments that measure runout
directly and to those that compute it from index measurements. It also gives recommendations for the
evaluation of tooth thickness measuring instruments and, of necessity, includes the estimation of
measurement uncertainty with the use of calibrated gear artifacts. It does not address the calibration of
artifacts by laboratories accredited in accordance with ISO/IEC 17025; nor are its requirements intended as an
acceptance specification of product gears (see ISO 1328-1, ISO 1328-2, ISO/TR 10064-1 and
ISO/TR 10064-2). The estimation of product gear measurement uncertainty is beyond its scope (see
ISO/TR 10064-5 for recommendations).
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 1328-1, Cylindrical gears — ISO system of accuracy — Part 1: Definitions and allowable values of
deviations relevant to corresponding flanks of gear teeth
ISO/TR 10064-3, Cylindrical gears — Code of inspection practice — Part 3: Recommendations relative to
gear blanks, shaft centre distance and parallelism of axes
1)
ISO/TR 10064-5 , Cylindrical gears — Code of inspection practice — Part 5: Recommendations relative to
evaluation of gear measuring instruments
ISO 14253-1, Geometrical Product Specifications (GPS) — Inspection by measurement of workpieces and
measuring equipment — Part 1: Decision rules for proving conformance or non-conformance with
specifications
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
3 Terms, definitions and symbols
For the purposes of this document, the following terms, definitions and symbols (see Table 1) apply.
NOTE 1 The definitions, when applicable, conform to ISO 122-1, ISO 1328-1, ISO 1328-2 and ISO/TR 10064-1.
NOTE 2 The terms, definitions and symbols used in this document may differ from those used in other International
Standards. The user needs to be certain of fully understanding them, as used here.

1) Under preparation.
3.1
accuracy
closeness of agreement between a measured value and an accepted reference (or calibrated) value
3.2
artifact
object of specific shape used to determine the accuracy of measuring devices
See Clause 7.
3.3
bias
difference between the observed average of measurements and the calibration value
See Figure 1.
NOTE Bias can be affected by systematic errors such as linearity or gain and can be different throughout the
operating range of the measurement system.

Key
1 calibration value
2 observed average
3 bias
Figure 1 — Bias
3.4
calibration
set of operations that establish, under specified conditions, the relationship between values of quantities
indicated by a measuring instrument or measuring system and the corresponding values realized by
standards
3.5
gain
magnification factor between the input and the output
3.6
helix artifact
artifact having a calibrated helix form
3.7
involute artifact
calibrated artifact having an involute form determined by a specific base circle
2 © ISO 2003 — All rights reserved

3.8
measurand
particular quantity subject to measurement
3.9
pitch and runout artifact
artifact with calibrated index features for pitch or runout or both
3.10
repeatability (of measurement results)
closeness of the agreement between results of successive measurements of the same measurand carried out
under the same conditions of measurement
3.11
reproducibility (of measurement results)
closeness of the agreement between results of measurements of the same measurand carried out under
changed conditions of measurement
NOTE 1 A valid statement of reproducibility requires specification of the conditions changed.
NOTE 2 The changed conditions may include
 principle of measurement,
 method of measurement,
 observer,
 measuring instrument,
 reference standard,
 location,
 conditions of use, and
 time.
NOTE 3 Reproducibility may be expressed quantitatively in terms of dispersion characteristics of the results.
3.12
uncertainty (of measurement results)
parameter associated with the result of a measurement that characterizes the dispersion of the values that
could be reasonably attributed to the measurand
NOTE 1 The parameter can be, for example, a standard deviation (or a given multiple of it), or the half-width of an
interval having a stated level of confidence.
NOTE 2 Uncertainty of measurement comprises, in general, many components. Some of these components can be
evaluated from the statistical distribution of the results of a series of measurements and can be characterized by
experimental standard deviations. The other components, which also can be characterized by standard deviations, are
evaluated from assumed probability distributions based on experience or other information.
NOTE 3 It is understood that the result of the measurement is the best estimate of the value of the measurand, and
that all components of uncertainty, including those arising from systematic effects, such as components associated with
corrections and reference standards, contribute to the dispersion.
Table 1 — Symbols
Symbol Definition Unit Where first
used
E Bias µm Eq. 1
k Coverage factor — Eq. 1
n Number of measurements — Eq. 2
U Measuring uncertainty µm Eq. 1

U Uncertainty estimation µm Eq. 4

95c
U Measurement uncertainty stated in reference artifact calibration document µm Eq. 3

95(cal)
u Standard uncertainty µm Eq. 1

m
u Reference artifact calibration uncertainty µm Eq. 1
n
u Geometry similarity influence µm Eq. 1

g
u Workpiece characteristic influence µm Eq. 1

w
X Individual measured value of parameter calibrated µm Eq. 2

i
X Mean of measured values µm Eq. 2

4 Application
4.1 General
The purpose of the tests prescribed in this standard is to estimate measurement uncertainty. It has been
assumed that the gear-measuring instrument has been installed on site and a series of acceptance tests have
been completed successfully. Prescribed tests may serve as interim checks to verify the measurement
process.
The measurement and evaluation procedures may be used as part of acceptance tests for a new gear-
measuring instrument, with prior agreement between customer and supplier. In this situation it is
recommended that a series of traceably calibrated gear artifacts be used to verify the measurement
uncertainty at specific points throughout the working volume of the instrument. These measurements should
include provision for testing the machine with table loads that represent the weight of product gears being
tested.
4.2 Traceability
The term traceability implies an unbroken calibration chain from measurements taken on shop floor inspection
instruments to the primary artifacts at a national laboratory, see Figure 2. Traceability is transferred by
calibrated gear artifacts. The primary laboratory has the lowest uncertainty, and uncertainty increases at each
level as the traceability chain is transferred to shop floor measuring instruments. Minimizing the steps from the
primary laboratory to a shop floor measuring instrument will reduce the measurement uncertainty.
4.3 Artifacts
The gear artifacts used for these tests shall be of similar size and geometry to product gears inspected on the
measuring instrument. Artifacts shall be used to evaluate the accuracy of each parameter inspected: helix
(lead), profile, pitch, runout and tooth thickness. Specific artifact requirements are given in Clause 7.
4 © ISO 2003 — All rights reserved

4.4 Measurement uncertainty
Conventional practice recommends the uncertainty of a measurement process be less than 10 % of the
parameter tolerance measured, to ensure that the reliable interpretation of the measurement results is
possible. However, this is not technically achievable when inspecting high accuracy gears.
For example, in gears with tolerances better than 10 µm, the best achievable uncertainty may be only 20 to
30 %. To determine the uncertainty, see Clause 8 and ISO/TR 10064-5. Recommendations for allowable
measurement uncertainty are made in ISO/TR 10064-5.

Figure 2 — Hierarchy of calibration
4.5 Sources of uncertainty
The verification of measurement uncertainty shall include, but not be limited to, the assessment of the
principal contributions to uncertainty in gear measurement as follows:
 artifact data;
 calibration data;
 repeatability of the instrument;
 reproducibility of the instrument;
 probe system filtering, damping and dynamic response, and accuracy;
 environmental influence, including temperature, vibration;
 mechanical alignment;
 runout and mounting error measurement;
 servo control system;
 evaluation software;
 operator.
Refer to ISO/TS 14253-2 for further information on this subject.
4.6 Evaluation interval
The user shall establish the interval for evaluation of the measurement process. It is also recommended that
interim tests be performed on a designated artifact. Data produced by the interim tests on calibrated gear
artifacts can be used for measurement uncertainty.
5 Condition of the measurement system
5.1 System characteristics
Several characteristics of the measuring instrument and readout system should be checked or verified before
proceeding with artifact measurement.
5.2 Suitability for calibration
The instrument should be suitable for calibration and representative of the normal operating conditions.
5.2.1 Instrument alignment
When the instrument manufacturer provides procedural checks for verification of alignments, these checks
shall be made on a regular basis. Instrument alignment includes such things as runout of centres, whether the
centres are coaxial, parallelism of centre axis to instrument ways, squareness of ways, etc. See
ISO/TR 10064-5.
5.2.2 Readout condition
Meter movements and chart recorders should be checked to the manufacturer’s specifications such as
magnification, linearity, lost motion, and frequency response. See ISO/TR 10064-5.
5.3 Table load considerations
Instruments that are used to check very large gears (above 1 m) may deflect or change shape under the
weight of the part being tested. This will cause deviations in measurement. Such instruments should be
calibrated with a simulated load on the table. Gears with significant inertial mass can also cause measurement
deviations. The effects of driving methods such as centre size, friction characteristics, live or dead centres, etc.
should be considered.
5.4 Tooling and gauges
Any tooling or gauges used in the set up or calibration of a measuring instrument shall be calibrated at
suitable intervals.
6 © ISO 2003 — All rights reserved

6 Environment
The stability of the environment will affect accuracy of the calibration process and measurement of production
parts. The required environment specified by the instrument manufacturer shall be met during its evaluation
and use. Calibration requires an environment controlled to the extent necessary to assure continued
measurements of required accuracy considering temperature, humidity, vibration, cleanliness and other
controllable factors affecting precision measurement.
In particular, an adequate thermal equilibrium of the reference artifact and the instrument should exist. If
measurements of the reference artifact are taken with an ambient temperature other than that of its calibration
(normally 20 °C), either the calibrated value shall be adjusted to the actual operating temperature or the
measured values shall be corrected to the calibration temperature. This procedure will add significant sources
of uncertainty to the calibration process. See ISO/TR 10064-5 for details.
7 Artifacts
7.1 Artifact size and geometry
This clause describes artifacts for estimating measurement uncertainty. Artifacts are required for verifying
every parameter measured by an instrument, namely helix (lead), involute, pitch, runout and tooth thickness.
Artifacts may be work-piece-like, such as an accurate gear.
The specific requirements are prescribed in the following sections. Further recommendations, supporting
information and artifact design details are presented in ISO/TR 10064-5.
The minimum requirement is that the artifact size shall be selected as near as practical to the centre of the
measurement range over which the instrument is used.
Ideally, the geometry of the artifacts should represent the tooth number, module, helix angle, facewidth and
weight of the product gear range. The artifacts should have left and right flank features. Single flank artifacts
may be used inverted to simulate the opposite flank.
It is recommended that internal artifacts be used to verify instrument uncertainty where internal work pieces
are measured.
A key characteristic of reference artifacts is their geometric stability. Adequate stability is an inherent
requirement of the comparator method of measurement uncertainty determination. Since it is very difficult to
detect st
...

NORME ISO
INTERNATIONALE 18653
Première édition
2003-12-01
Engrenages — Évaluation des
instruments de mesure des engrenages
individuels
Gears — Evaluation of instruments for the measurement of individual
gears
Numéro de référence
©
ISO 2003
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©  ISO 2003
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ii © ISO 2003 — Tous droits réservés

Sommaire Page
Avant-propos. iv
1 Domaine d'application. 1
2 Références normatives. 1
3 Termes, définitions et symboles . 1
4 Application. 4
4.1 Généralités. 4
4.2 Traçabilité . 4
4.3 Artefacts. 4
4.4 Incertitude de mesure. 5
4.5 Sources d'incertitude. 5
4.6 Intervalle d'évaluation. 6
5 État du système de mesure. 6
5.1 Caractéristiques du système . 6
5.2 Aptitude à l'étalonnage. 6
5.3 Considérations relatives à la charge de la table.6
5.4 Outillage et calibres . 6
6 Environnement . 7
7 Artefacts. 7
7.1 Taille et forme géométrique des artefacts. 7
7.2 Artefacts de développante de cercle . 9
7.3 Artefacts d'hélice . 9
7.4 Artefacts de pas . 10
7.5 Artefacts de faux-rond de rotation . 11
7.6 Artefacts d'épaisseur de denture . 11
7.7 Artefacts de pièces grandeur nature . 12
8 Méthode d'estimation de l'incertitude de mesure. 13
8.4 Méthodes. 14
8.5 Méthode par comparaison . 14
8.6 Calcul de l'incertitude de mesure U . 14
8.7 Mode opératoire . 15
Annexe A (normative) Exigences relatives aux certificats d'étalonnage des artefacts. 18
Bibliographie . 20

Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes nationaux de
normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est en général confiée
aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude a le droit de faire partie du
comité technique créé à cet effet. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec l'ISO participent également aux travaux. L'ISO collabore étroitement avec
la Commission électrotechnique internationale (CEI) en ce qui concerne la normalisation électrotechnique.
Les Normes internationales sont rédigées conformément aux règles données dans les Directives ISO/CEI,
Partie 2.
La tâche principale des comités techniques est d'élaborer les Normes internationales. Les projets de Normes
internationales adoptés par les comités techniques sont soumis aux comités membres pour vote. Leur
publication comme Normes internationales requiert l'approbation de 75 % au moins des comités membres
votants.
L'attention est appelée sur le fait que certains des éléments du présent document peuvent faire l'objet de
droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable de ne
pas avoir identifié de tels droits de propriété et averti de leur existence.
L'ISO 18653 a été élaborée par le comité technique ISO/TC 60, Engrenages.

iv © ISO 2003 — Tous droits réservés

NORME INTERNATIONALE ISO 18653:2003(F)

Engrenages — Évaluation des instruments de mesure des
engrenages individuels
1 Domaine d'application
La présente Norme internationale spécifie des méthodes d'évaluation des instruments utilisés pour mesurer la
développante de cercle, l'hélice, le pas et le faux-rond de rotation des engrenages. Elle est applicable aussi
bien aux instruments qui mesurent le faux-rond directement qu'à ceux qui le calculent à partir de mesures de
divisions. La présente Norme internationale donne également des recommandations sur l'évaluation des
instruments de mesure de l'épaisseur des dents et, nécessairement, elle inclut une estimation de l'incertitude
de mesure à l'aide d'artefacts d'engrenages calibrés. Elle ne traite cependant pas de l'étalonnage des
artefacts par des laboratoires accrédités conformément à l'ISO/CEI 17025, et ses exigences ne sont pas
destinées à servir de base à l'acceptation des engrenages fabriqués (voir l'ISO 1328-1, l'ISO 1328-2,
l'ISO/TR 10064-1 et l'ISO/TR 10064-2). L'estimation de l'incertitude de mesure des engrenages fabriqués
n'entre pas dans son domaine d'application (voir pour cela l'ISO/TR 10064-5).
2 Références normatives
Les documents de référence suivants sont indispensables pour l'application du présent document. Pour les
références datées, seule l'édition citée s'applique. Pour les références non datées, la dernière édition du
document de référence s'applique (y compris les éventuels amendements).
ISO 1328-1:1998, Engrenages cylindriques — Système ISO de précision — Partie 1: Définitions et valeurs
admissibles des écarts pour les flancs homologues de la denture
ISO/TR 10064-3, Engrenages cylindriques — Code pratique de réception — Partie 3: Recommandations
relatives au corps de roues, à l'entraxe et au parallélisme des axes
1)
ISO/TR 10064-5 , Engrenages cylindriques — Code pratique de réception — Partie 5: Recommandations
relatives à l'évaluation des instruments de mesure des engrenages
ISO 14253-1, Spécification géométrique des produits (GPS) — Vérification par la mesure des pièces et des
équipements de mesure — Partie 1: Règles de décision pour prouver la conformité ou la non-conformité à la
spécification
ISO/CEI 17025, Prescriptions générales concernant la compétence des laboratoires d'étalonnages et d'essais
3 Termes, définitions et symboles
Pour les besoins du présent document, les termes, définitions et symboles (voir Tableau 1) suivants
s'appliquent.
NOTE 1 Le cas échéant, les définitions sont conformes à l'ISO 1122-1, l'ISO 1328-1, l'ISO 1328-2 et à
l'ISO/TR 10064-1.
1)
À publier.
NOTE 2 Les termes, définitions et symboles utilisés dans ce document peuvent être différents de ceux utilisés dans
d'autres Normes internationales. Il est nécessaire que l'utilisateur soit sûr de leur bonne compréhension.
3.1
exactitude
étroitesse de l'accord entre une valeur mesurée et une valeur de référence (ou calibrée) acceptée
3.2
artefact
objet de forme spécifique utilisé pour déterminer l'exactitude des instruments de mesure
Voir Article 7.
3.3
biais
différence entre la moyenne des mesures observées et la valeur d'étalonnage
Voir Figure 1.
NOTE Le biais peut être affecté par des erreurs systématiques telles que la linéarité ou le gain et peut être différent
sur la totalité de l'étendue de mesure du système.

Légende
1 valeur d'étalonnage
2 moyenne observée
3 biais
Figure 1 — Biais
3.4
étalonnage
ensemble d'opérations qui définissent, dans certaines conditions, la relation entre les valeurs des grandeurs
indiquées par un instrument de mesure ou un système de mesure et les valeurs correspondantes réalisées
par des étalons
3.5
gain
facteur d'amplification entre une valeur d'entrée et une valeur de sortie
3.6
artefact d'hélice
artefact ayant une forme d'hélice étalonnée
2 © ISO 2003 — Tous droits réservés

3.7
artefact de développante de cercle
artefact étalonné ayant une forme de développante de cercle déterminée par un cercle de base spécifique
3.8
mesurande
grandeur particulière soumise à mesurage
3.9
artefact de pas et de faux-rond de rotation
artefact ayant des caractéristiques d'index étalonnées pour le pas, le faux-rond de rotation ou les deux
3.10
répétabilité (des résultats de mesures)
étroitesse de l'accord entre les résultats de mesures successives du même mesurande effectuées dans les
mêmes conditions de mesure
3.11
reproductibilité (des résultats de mesures)
étroitesse de l'accord entre les résultats de mesures du même mesurande effectuées dans des conditions de
mesure différentes
NOTE 1 Pour être valide, une indication de la reproductibilité requiert la spécification des conditions modifiées.
NOTE 2 La modification des conditions peut porter sur
 le principe de mesure,
 la méthode de mesure,
 l'observateur,
 l'instrument de mesure,
 l'étalon de référence,
 le lieu,
 les conditions d'utilisation, et
 le temps.
NOTE 3 La reproductibilité peut s'exprimer quantitativement en termes de dispersion des résultats.
3.12
incertitude (des résultats d'une mesure)
paramètre associé au résultat d'une mesure et qui caractérise la dispersion des valeurs qui pourraient
raisonnablement être attribuées au mesurande
NOTE 1 Ce paramètre peut, par exemple, être un écart-type (ou un multiple de celui-ci) ou la demi-largeur d'un
intervalle à un niveau de confiance donné.
NOTE 2 L'incertitude de mesure se compose en général de plusieurs éléments. Certaines de ces composantes
peuvent être évaluées à partir de la distribution statistique des résultats d'une série de mesures et caractérisées par des
écarts-types expérimentaux. D'autres composantes, qui peuvent également être caractérisées par des écarts-types, sont
évaluées à partir d'hypothèses probabilistes reposant sur l'expérience ou d'autres informations.
NOTE 3 Il est admis qu'un résultat de mesure est la meilleure estimation de la valeur du mesurande et que toutes les
composantes de l'incertitude contribuent à la dispersion, y compris celles qui résultent d'effets systématiques telles que
les composantes associées aux corrections et aux étalons de référence.
Tableau 1 — Symboles
Symbole Définition Unités Première
utilisation
E Biais µm Éq. 1
k Facteur d'élargissement — Éq. 1
n Nombre de mesures — Éq. 2
U
Incertitude de mesure µm Éq. 1
U Estimation de l'incertitude µm Éq. 4
95c
U Incertitude de mesure indiquée dans le document µm Éq. 3
95(cal)
d'étalonnage de l'artefact de référence
u Incertitude type µm Éq. 1
m
u Incertitude d'étalonnage de l'artefact de référence µm Éq. 1
n
u Influence de la similitude géométrique µm Éq. 1
g
u
Influence des caractéristiques de la pièce µm Éq. 1
w
X Valeur mesurée isolée du paramètre étalonné µm Éq. 2
i
Moyenne des valeurs mesurées µm Éq. 2
X
4 Application
4.1 Généralités
Les essais prescrits dans la présente Norme internationale ont pour objet d'estimer l'incertitude de mesurage.
Il est posé en hypothèse que l'instrument de mesure des engrenages a été installé sur le site et a subi avec
succès un certain nombre d'essais de réception. Les essais prescrits peuvent servir de contrôles
intermédiaires pour vérifier le processus de mesurage.
Les modes opératoires de mesure et d'évaluation peuvent être utilisés pour les essais de réception d'un
nouvel instrument de mesure des engrenages si le client et le fournisseur en conviennent préalablement.
Dans ce cas, il est recommandé d'utiliser une série d'artefacts d'engrenages étalonnés de façon traçable pour
vérifier l'incertitude de mesure en certains points particuliers du volume de travail de l'instrument. Il est
recommandé que ces mesures prévoient l'essai de la machine avec des charges s'exerçant sur la table
représentatives du poids des engrenages fabriqués essayés.
4.2 Traçabilité
Le terme traçabilité implique l'existence d'une chaîne d'étalonnage non interrompue entre les mesures faites
sur des instruments en atelier et celles faites sur des étalons dans un laboratoire national, voir Figure 2. Cette
traçabilité est assurée par des artefacts d'engrenages étalonnés. C'est le laboratoire détenteur de l'étalon
primaire qui a l'incertitude la plus faible, et l'incertitude augmente de niveau en niveau de transfert de la
chaîne d'étalonnage jusqu'aux instruments de mesure en atelier. Moins il y a d'étapes entre l'étalon de
laboratoire primaire et l'instrument de mesure d'atelier et plus faible sera l'incertitude de mesure.
4.3 Artefacts
Les artefacts d'engrenages utilisés pour ces essais doivent être similaires de forme et de dimensions aux
engrenages fabriqués contrôlés par l'instrument de mesure. Les artefacts doivent être utilisés pour évaluer
l'exactitude de chacun des paramètres inspectés: hélice (pas hélicoïdal), profil, pas, faux-rond de rotation et
épaisseur de dentures. Les exigences particulières relatives aux artefacts sont indiquées à l'Article 7.
4 © ISO 2003 — Tous droits réservés

4.4 Incertitude de mesure
Les pratiques classiques recommandent que l'incertitude d'un processus de mesure soit inférieure à 10 % de
la tolérance du paramètre mesuré pour assurer une interprétation fiable des résultats de mesure. Cette
recommandation n'est toutefois pas techniquement possible avec les engrenages de haute précision.
Lorsque, par exemple, les engrenages ont une tolérance meilleure que 10 µm, l'incertitude la meilleure
possible ne peut être que de 20 % à 30 %. Pour déterminer l'incertitude, voir l'Article 8 et l'ISO/TR 10064-5.
Des recommandations sur l'incertitude admissible de mesure sont données dans l'ISO/TR 10064-5.

Figure 2 — Hiérarchie d'étalonnage
4.5 Sources d'incertitude
La vérification de l'incertitude de mesure doit inclure, sans s'y limiter, l'évaluation des apports principaux à
l'incertitude dans les mesures sur engrenages indiquées ci-dessous:
 données sur les artefacts;
 données d'étalonnage;
 répétabilité de l'instrument;
 reproductibilité de l'instrument;
 filtrage, amortissement, réponse dynamique et exactitude du système de palpeur;
 influence de l'environnement, à l'exception de la température et des vibrations;
 alignement mécanique;
 mesurage du faux-rond de rotation et de l'erreur de montage;
 système de servocommande;
 logiciel d'évaluation;
 opérateur.
Voir l'ISO/TS 14253-2 pour de plus amples renseignements sur le sujet.
4.6 Intervalle d'évaluation
L'utilisateur doit définir l'intervalle d'évaluation du processus de mesurage. Il est également recommandé
d'effectuer des essais intermédiaires sur un artefact désigné. Les données fournies par ces essais
intermédiaires sur des artefacts d'engrenages étalonnés peuvent servir pour déterminer l'incertitude de
mesure.
5 État du système de mesure
5.1 Caractéristiques du système
Il convient de contrôler ou de vérifier plusieurs caractéristiques du système de mesure et du système de
lecture avant de procéder aux mesures sur artefacts.
5.2 Aptitude à l'étalonnage
Il convient que l'instrument puisse être étalonné et représentatif des conditions de fonctionnement normal.
5.2.1 Alignement de l'instrument
Lorsque le fabricant prévoit des contrôles de procédure pour la vérification des alignements, ces contrôles
doivent être faits à intervalles réguliers. L'alignement des instruments comprend des vérifications du type
contrôle du faux-rond de rotation des trous de centre, de leur coaxialité, du parallélisme de l'axe central et des
glissières de guidage de l'instrument, de la perpendicularité des glissières, etc. Voir l'ISO/TR 10064-5.
5.2.2 Conditions de lecture
Il convient de vérifier que les mouvements des appareils de mesure et les enregistreurs graphiques sont
conformes aux spécifications du fabricant sur les points tels que le grossissement, la linéarité, la perte dans
les mouvements et la réponse en fréquences. Voir l'ISO/TR 10064-5.
5.3 Considérations relatives à la charge de la table
Les instruments utilisés pour vérifier de très gros engrenages (plus de 1 m) peuvent fléchir ou changer de
forme sous le poids de la pièce essayée. D'où des écarts de mesure. Il convient d'étalonner ces instruments
en simulant la charge qui s'exerce sur la table. Les engrenages à masse d'inertie importante peuvent
également provoquer des écarts de mesure. Il convient de prendre en compte les effets des méthodes
d'entraînement telles que la taille des trous de centre, les caractéristiques de frottement, les trous de centre
actifs ou morts, etc.
5.4 Outillage et calibres
Tous les outils et calibres utilisés pour le réglage ou l'étalonnage des instruments de mesure doivent être
étalonnés à intervalles convenables.
6 © ISO 2003 — Tous droits réservés

6 Environnement
La stabilité de l'environnement joue sur l'exactitude du processus d'étalonnage et la mesure des pièces de
production. L'environnement requis spécifié par le fabricant d'instruments doit être respecté pendant
l'évaluation et l'utilisation de ces derniers. L'étalonnage exige un environnement contrôlé dans les limites
nécessaires pour assurer un mesurage continu de l'exactitude requise, à savoir la température, l'humidité, les
vibrations, la propreté et autres facteurs contrôlables affectant les mesures de fidélité.
Il convient en particulier d'établir un équilibre thermique convenable entre l'artefact de référence et l'instrument.
Si les mesures sont faites sur l'artefact de référence à une température ambiante autre que celle de
l'étalonnage (normalement 20 °C), il faut soit ajuster la valeur étalonnée à la température réelle de service,
soit corriger les valeurs mesurées pour les rapporter à la température d'étalonnage. Ces opérations ajoutent
des sources significatives d'incertitude au processus d'étalonnage. Voir l'ISO/TR 10064-5 pour les détails.
7 Artefacts
7.1 Taille et forme géométrique des artefacts
Le présent article décrit les artefacts utilisés pour l'estimation de l'incertitude de mesure. Les artefacts sont
nécessaires pour vérifier chacun des paramètres mesurés par un instrument, à savoir l'hélice (pas), la
développante de cercle, le pas, le faux-rond de rotation et l'épaisseur des dents. Les artefacts peuvent être de
vraies pièces, un engrenage exact par exemple.
Les exigences particulières sont indiquées dans les paragraphes qui suivent. D'autres recommandations
venant à l'appui des informations et des détails de conception des artefacts sont présentées dans
l'ISO/TR 10064-5.
L'exigence minimale est de choisir une taille d'artefact aussi voisine que possible du milieu de l'étendue de
mesure pour laquelle l'instrument est utilisé.
Idéalement, il convient que la forme géométrique des artefacts représente le nombre de dents, le module,
l'angle d'hélice, la largeur de denture et le poids de l'engrenage fabriqué. Il est recommandé que les artefacts
aient les caractéristiques des flancs gauche et droit. Des artefacts à flanc unique peuvent être utilisés pour
simuler le flanc homologue.
Il est recommandé pour vérifier l'incertitude des instruments d'utiliser des artefacts internes lorsque la mesure
porte sur des pièces internes.
La caractéristique essentielle des artefacts de référence est leur stabilité géométrique. Une stabilité suffisante
est une exigence inhérente à la méthode de détermination de l'incertitude de mesure par comparaison. Dans
la mesure où il est très difficile de détecter les problèmes de stabilité des artefacts pendant leur utilisation, il
est important de confirmer que leur conception, leur fabrication et leur maniement se sont effectués de
manière à réduire le plus possible l'instabilité. Il est recommandé d'utiliser des artefacts multi
...