SIST-TS CEN ISO/TS 14253-4:2014

Geometrical product specifications (GPS) - Inspection by measurement of workpieces and measuring equipment - Part 4: Background on functional limits and specification limits in decision rules (ISO/TS 14253-4:2010)

This part of ISO 14253 outlines the main assumptions behind the theoretically ideal decision rules established in ISO 14253-1. It discusses why these rules have to be the default rules and what considerations should be taken into account before applying different decision rules. This part of ISO 14253 applies to all specifications defined in general GPS standards (see ISO/TR 14638), i.e. standards prepared by ISO/TC 213, including
- workpiece specifications (usually given as specification limits), and
- measuring equipment specifications (usually given as maximum permissible errors).

Geometrische Produktspezifikation (GPS) - Prüfung von Werkstücken und Messgeräten durch Messen - Teil 4: Aspekte zur Auswahl von Entscheidungsregeln (ISO/TS 14253-4:2010)

Dieser Teil von ISO 14253 erfasst die wichtigsten Annahmen, die den Hintergrund für die in ISO 14253-1
festgelegten theoretisch idealen Entscheidungsregeln bilden. Es wird erörtert, warum diese Regeln Default-
Regeln sind und welche Betrachtungen angestellt werden sollten, bevor andere Entscheidungsregeln
angewendet werden.
Dieser Teil von ISO 14253 gilt für alle Spezifikationen, die in den allgemeinen GPS Normen definiert sind
(siehe ISO/TR 14638), d. h. Normen, die von ISO/TC 213 erstellt wurden, einschließlich der
⎯ Spezifikationen für Werkstücke (im Allgemeinen als Spezifikationsgrenzen angegeben) und
⎯ Spezifikationen für Messgeräte (im Allgemeinen als maximal zulässige Fehler angegeben).

Spécification géométrique des produits (GPS) - Vérification par la mesure des pièces et des équipements de mesure - Partie 4: Informations de base sur les limites fonctionnelles et les limites de spécification dans les règles de décision (ISO/TS 14253-4:2010)

L'ISO 14253-4:2010 décrit les grandes lignes des principales hypothèses sous-jacentes aux règles de décision théoriquement idéales établies dans l'ISO 14253-1. Elle expose les raisons pour lesquelles ces règles sont celles à utiliser par défaut, ainsi que les considérations à prendre en compte avant d'appliquer d'autres règles de décision.
L'ISO 14253-4:2010 s'applique à toutes les spécifications définies dans les normes GPS générales (voir l'ISO/TR 14638), c'est-à-dire les normes préparées par l'ISO/TC 213, y compris:
les spécifications de pièces (généralement exprimées sous forme de limites de spécification), et
les spécifications d'équipements de mesure (généralement exprimées en erreurs maximales tolérées).

Specifikacija geometrijskih veličin izdelka - Kontrola z merjenjem obdelovancev in merilna oprema - 4. del: Merila za izbiro funkcionalnih omejitev ter omejitev pri odločanju (ISO/TS 14253-4:2010)

Ta del standarda ISO 14253 podaja glavne predpostavke za teoretično idealnimi pravili odločanja, vzpostavljenimi v standardu ISO 14253-1. Opisuje, zakaj so ta pravila privzeta pravila in katere predpostavke se upoštevajo pred uporabo posameznih pravil odločanja. Ta del standarda ISO 14253 velja za vse specifikacije, opredeljene v standardih o splošni specifikaciji geometrijskih veličin izdelka (glejte ISO/TR 14638), tj. standardih, ki jih pripravlja ISO/TC 213, vključno s:
– specifikacijami obdelovancev (običajno podanimi kot specifikacijske mejne vrednosti) in
– specifikacijami merilne opreme (običajno podanimi kot največje število dovoljenih napak).

General Information

• Status: Published
• Publication Date: 26-May-2014
• 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: 14-May-2014
• Due Date: 19-Jul-2014
• Completion Date: 27-May-2014
• Ref Project: CEN ISO/TS 14253-4:2010 - Geometrical product specifications (GPS) - Inspection by measurement of workpieces and measuring equipment - Part 4: Background on functional limits and specification limits in decision rules (ISO/TS 14253-4:2010)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST-TS CEN ISO/TS 14253-4:2014
01-julij-2014
6SHFLILNDFLMDJHRPHWULMVNLKYHOLþLQL]GHOND.RQWUROD]PHUMHQMHPREGHORYDQFHYLQ
PHULOQDRSUHPDGHO0HULOD]DL]ELURIXQNFLRQDOQLKRPHMLWHYWHURPHMLWHYSUL
RGORþDQMX,6276
Geometrical product specifications (GPS) - Inspection by measurement of workpieces
and measuring equipment - Part 4: Background on functional limits and specification
limits in decision rules (ISO/TS 14253-4:2010)
Geometrische Produktspezifikation (GPS) - Prüfung von Werkstücken und Messgeräten
durch Messen - Teil 4: Aspekte zur Auswahl von Entscheidungsregeln (ISO/TS 14253-
4:2010)
Spécification géométrique des produits (GPS) - Vérification par la mesure des pièces et
des équipements de mesure - Partie 4: Informations de base sur les limites
fonctionnelles et les limites de spécification dans les règles de décision (ISO/TS 14253-
4:2010)
Ta slovenski standard je istoveten z: CEN ISO/TS 14253-4:2010
ICS:
17.040.30 Merila Measuring instruments
17.040.40 6SHFLILNDFLMDJHRPHWULMVNLK Geometrical Product
YHOLþLQL]GHOND*36 Specification (GPS)
SIST-TS CEN ISO/TS 14253-4:2014 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TS CEN ISO/TS 14253-4:2014

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SIST-TS CEN ISO/TS 14253-4:2014


TECHNICAL SPECIFICATION
CEN ISO/TS 14253-4

SPÉCIFICATION TECHNIQUE

TECHNISCHE SPEZIFIKATION
May 2010
ICS 17.040.01
English Version
Geometrical product specifications (GPS) - Inspection by
measurement of workpieces and measuring equipment - Part 4:
Background on functional limits and specification limits in
decision rules (ISO/TS 14253-4:2010)
Spécification géométrique des produits (GPS) - Vérification Geometrische Produktspezifikationen (GPS) - Prüfung von
par la mesure des pièces et des équipements de mesure -
Werkstücken und Messgeräten durch Messen - Teil 4:
Partie 4: Informations de base sur les limites fonctionnelles Grundlagen für Funktionsgrenzen und
et les limites de spécification dans les règles de décision Spezifikationsgrenzen in Entscheidungsregeln (ISO/TS
(ISO/TS 14253-4:2010) 14253-4:2010)
This Technical Specification (CEN/TS) was approved by CEN on 4 April 2010 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available
promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)
until the final decision about the possible conversion of the CEN/TS into an EN is reached.

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
© 2010 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/TS 14253-4:2010: E
worldwide for CEN national Members.

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SIST-TS CEN ISO/TS 14253-4:2014
CEN ISO/TS 14253-4:2010 (E)
Contents Page
Foreword .3

2

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SIST-TS CEN ISO/TS 14253-4:2014
CEN ISO/TS 14253-4:2010 (E)
Foreword
This document (CEN ISO/TS 14253-4:2010) 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.
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.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to announce this Technical Specification: 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/TS 14253-4:2010 has been approved by CEN as a CEN ISO/TS 14253-4:2010 without any
modification.

3

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SIST-TS CEN ISO/TS 14253-4:2014

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SIST-TS CEN ISO/TS 14253-4:2014

TECHNICAL ISO/TS
SPECIFICATION 14253-4
First edition
2010-05-15

Geometrical product specifications
(GPS) — Inspection by measurement of
workpieces and measuring equipment —
Part 4:
Background on functional limits and
specification limits in decision rules
Spécification géométrique des produits (GPS) — Vérification par la
mesure des pièces et des équipements de mesure —
Partie 4: Informations de base sur les limites fonctionnelles et les limites
de spécification dans les règles de décision




Reference number
ISO/TS 14253-4:2010(E)
©
ISO 2010

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SIST-TS CEN ISO/TS 14253-4:2014
ISO/TS 14253-4:2010(E)
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©  ISO 2010
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
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Published in Switzerland

ii © ISO 2010 – All rights reserved

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SIST-TS CEN ISO/TS 14253-4:2014
ISO/TS 14253-4:2010(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Definitions .1
4 Relationship between functional limits and specification limits.2
4.1 General .2
4.2 The one-sided case .2
4.3 The two-sided case .6
5 How functional limits are determined .9
5.1 Ideal situation .9
5.2 Use of earlier models .9
5.3 Reverse engineering .9
5.4 Trial and error .10
5.5 Method based on a set of working examples.10
6 Specification limits and how specification limits are determined relative to functional
limits .10
6.1 General .10
6.2 Ideal situation .10
6.3 Specification reduced by assumed measurement uncertainty .10
6.4 Specification reduced by an arbitrary amount.11
7 Shape of assumed functional deterioration curve.11
7.1 Ideal situation .11
7.2 Gradual deterioration.11
8 Determining specification limits .12
8.1 Ideal situation .12
8.2 Batch parts made by desired process .12
9 Alternative basis for decision rules.12
9.1 General .12
9.2 Alternative decision rules.12
9.3 Choice of alternative decision rules.13
Annex A (informative) Relation to the GPS matrix model.14
Bibliography.16

© ISO 2010 – All rights reserved iii

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SIST-TS CEN ISO/TS 14253-4:2014
ISO/TS 14253-4:2010(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.
In other circumstances, particularly when there is an urgent market requirement for such documents, a
technical committee may decide to publish other types of document:
⎯ an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in
an ISO working group and is accepted for publication if it is approved by more than 50 % of the members
of the parent committee casting a vote;
⎯ an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical
committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting
a vote.
An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a
further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is
confirmed, it is reviewed again after a further three years, at which time it must either be transformed into an
International Standard or be withdrawn.
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/TS 14253-4 was prepared by Technical Committee ISO/TC 213, Dimensional and geometrical product
specifications and verification.
ISO 14253 consists of the following parts, under the general title Geometrical product specifications (GPS) —
Inspection by measurement of workpieces and measuring equipment:
⎯ Part 1: Decision rules for proving conformance or non-conformance with specifications
⎯ Part 2: Guidance for the estimation of uncertainty in GPS measurement, in calibration of measuring
equipment and in product verification
⎯ Part 3: Guidelines for achieving agreements on measurement uncertainty statements
⎯ Part 4: Background on functional limits and specification limits in decision rules [Technical Specification]
iv © ISO 2010 – All rights reserved

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SIST-TS CEN ISO/TS 14253-4:2014
ISO/TS 14253-4:2010(E)
Introduction
This part of ISO 14253 is a geometrical product specifications (GPS) standard and is to be regarded as a
global GPS standard (see ISO/TR 14638). It influences the chain links 3, 4, 5 and 6 of all chains of general
GPS standards.
For more detailed information on the relation of this part of ISO 14253 to other standards and the GPS matrix
model, see Annex A.
The decision rules given in ISO 14253-1, which apply unless otherwise specified, are designed to ensure that
workpieces and measuring equipment are within the specification and that disputes over whether workpieces
and measuring equipment are within the specification can be avoided.
In order for the decision rules to work as designed, it is important to first give proof of conformance. In other
words, the user/buyer of the product in question should always require the manufacturer/supplier/seller of the
product to provide proof of conformance with the product.
If subsequent incoming inspection proves nonconformance, uncertainty budgets can be examined according
to ISO 14253-3 for mutual assurance of their validity. If it is concluded that both uncertainty budgets are valid,
the only conclusion is that one or the other or both measurement results are unrepresentative for the
measurement process in question.
If, for some reason, the user of the product does not want the supplier to provide the first proof, but instead
relies on incoming inspection, the user should reduce the functional limits by the measurement uncertainty of
the incoming inspection to arrive at the contractual specification limits that are communicated to, and
negotiated and agreed with, the supplier.
A separate problem is that of the reseller, who purchases product from a manufacturer and resells it to the
user. The decision rules given in ISO 14253-1 will function correctly if the reseller requires the manufacturer of
the product to provide proof of conformance and subsequently provides that proof to the user. If the reseller
for some reason decides to prove conformance to the user independently, there will be cases where neither
conformance nor nonconformance can be proven, so the reseller can neither return nor resell the product
based on the original specification. Consequently, this approach is not recommended.
The decision rules in ISO 14253-1 are also based on a number of assumptions. When these assumptions are
not true, these decision rules may not be economically optimal. This part of ISO 14253 outlines these
assumptions and discusses why they are the theoretically ideal assumptions.
For workpieces, only the creator of the specification (the designer) can be expected to know whether the
assumptions are true. Therefore, any deviations from the ISO 14253-1 decision rules can only be initiated and
documented by the specification owner.
For measuring equipment, a specification may be based on a standard, written unilaterally by the
manufacturer or purchaser of the equipment or written in cooperation between the manufacturer and the
purchaser of the equipment. If the specification is based on an ISO standard, and the standard does not
indicate other decision rules, the rules of ISO 14253-1 apply. In other cases, the decision rules can only be
documented by the specification author(s).
It must be recognized that the decision rules, whether they are given implicitly or explicitly, are part of the
specification.
It must further be recognized that the issues involved in choosing the optimal set of decision rules are
complicated and that it is unrealistic to expect that simple rules can suit every circumstance. Parties should
ensure access to competent technical resources before deviating from the ISO 14253-1 decision rules.
© ISO 2010 – All rights reserved v

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SIST-TS CEN ISO/TS 14253-4:2014
ISO/TS 14253-4:2010(E)
In this case, the specification owner must explicitly recognize that decision rules other than those defined in
ISO 14253-1 apply, and that documentation of this policy needs to be prepared and be made available to
trading partners (customers and/or suppliers) and be referenced in the technical product documentation.

vi © ISO 2010 – All rights reserved

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SIST-TS CEN ISO/TS 14253-4:2014
TECHNICAL SPECIFICATION ISO/TS 14253-4:2010(E)

Geometrical product specifications (GPS) — Inspection by
measurement of workpieces and measuring equipment —
Part 4:
Background on functional limits and specification limits in
decision rules
1 Scope
This part of ISO 14253 outlines the main assumptions behind the theoretically ideal decision rules established
in ISO 14253-1. It discusses why these rules have to be the default rules and what considerations should be
taken into account before applying different decision rules.
This part of ISO 14253 applies to all specifications defined in general GPS standards (see ISO/TR 14638),
i.e. standards prepared by ISO/TC 213, including
⎯ workpiece specifications (usually given as specification limits), and
⎯ measuring equipment specifications (usually given as maximum permissible errors).
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 14253-1:1998, Geometrical Product Specifications (GPS) — Inspection by measurement of workpieces
and measuring equipment — Part 1: Decision rules for proving conformance or non-conformance with
specifications
3 Definitions
3.1
reverse engineering
design process that consists in analysing the shape, dimensions and function of a finished part or prototype
and using this information to produce a similar product
3.2
product functional level
how well the product functions overall
3.3
product attribute functional level
how well the product functions with regard to a particular attribute
NOTE The overall product functional level depends on the product attribute functional levels for all the product
attributes.
© ISO 2010 – All rights reserved 1

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SIST-TS CEN ISO/TS 14253-4:2014
ISO/TS 14253-4:2010(E)
3.4
workpiece functional level
how well a product made up of the workpiece in question and a set of acceptable workpieces functions overall
3.5
workpiece characteristic functional level
how well a product made up of the workpiece in question and a set of acceptable workpieces functions with
regard to the attributes influenced by the characteristic in question
NOTE The overall workpiece functional level depends on the workpiece characteristic functional levels for all the
workpiece characteristics.
3.6
functional level of metrological characteristic
how well a measuring equipment with the metrological characteristic in question and a set of acceptable
metrological characteristics functions with regard to the attributes influenced by the characteristic in question
3.7
functional deterioration curve
graphical representation of the relationship between the product (attribute) functional level and the value of a
geometrical characteristic, a combination of geometrical characteristics or a metrological characteristic
NOTE In general, the translation from product attribute functional level to derived functional limits for geometrical
characteristics or metrological characteristics is not perfect. Correlation uncertainty (see ISO/TS 17450-2) quantifies this
imperfection.
4 Relationship between functional limits and specification limits
4.1 General
The management policy for determining specification limits (the specification limit operator) determines the
relationship between the functional limits and the specification limits that are specified on the drawing.
In many cases, several workpieces and several features and characteristics of those features on each
workpiece contribute to a given function.
Choosing the right characteristics of the right features for the specification is crucial for ensuring that the
specification is functionally relevant. It is the responsibility of the specification creator to select the functionally
relevant characteristics for the specification.
Most functions depend on a one-sided specification limit. For example, the ability of a shaft to fit into a given
hole depends on its diameter not being too large. There is no lower limit on the range of diameters that can fit
into the hole. The lower limit of the specification for the diameter of such a shaft serves an entirely different
function, e.g. that the shaft may not fit too loosely, the interface may not leak, or the shaft may not be too
weak.
4.2 The one-sided case
The theoretically ideal assumption that is used for defining fundamental rules in GPS, including the decision
rules defined in ISO 14253-1, is that the specification limits are equal to the functional limits and that the
function of the workpiece is 100 % when the specification limit is not exceeded and 0 % when it is exceeded
(see Figure 1).
2 © ISO 2010 – All rights reserved

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SIST-TS CEN ISO/TS 14253-4:2014
ISO/TS 14253-4:2010(E)
A
100 %
C
0 %
SL
B

Key
A workpiece characteristic functional level
B characteristic value
C workpiece conforms
SL specification limit
NOTE For an upper specification limit, the workpiece function is 100 % (full functionality) when the specified
characteristic value is below the specification limit (SL) and 0 % when the specified characteristic value is above the
specification limit (SL). The situation is similar, but reversed, for a lower specification limit.
Figure 1 — One-sided case with specification limit equal to functional limit
The workpiece functional level deterioration curve generally has a different shape from that shown in Figure 1
(see Figure 2). This functional level curve may represent the diameter of a shaft whose function it is to fit into
a hole. As the diameter becomes too large, the functional level deteriorates rapidly because the shaft no
longer fits into the hole.
A
100 %
0 %
B

Key
A workpiece characteristic functional level
B characteristic value
NOTE 1 The abore is an example of an upper functional limit where the workpiece function deteriorates gradually as
the specified characteristic value is increased beyond the range where it is 100 %. The situation is similar, but reversed,
for a lower specification limit.
NOTE 2 The “tail” can either represent the situation where a press fit still allows assembly with a perfect counterpart, or
the situation where variation in the counterpart still allows assembly, as the function of fit is dependent on the difference
between the two sizes rather than on the one size only.
Figure 2 — One-sided case with deteriorating functional level of workpiece
© ISO 2010 – All rights reserved 3

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SIST-TS CEN ISO/TS 14253-4:2014
ISO/TS 14253-4:2010(E)
The functional level deterioration curve has different shapes and deteriorate at different rates for different
functions (see Figure 3).
A
100 %
0 %
B

Key
A workpiece characteristic functional level
B characteristic value
NOTE For different functions, the workpiece function degrades gradually at different rates as the specified
characteristic value is increased beyond the range where it is 100 %.
Figure 3 — One-sided case with different deteriorating functional levels of workpiece
In the cases shown in Figures 2 and 3, it is necessary to define a minimum acceptable functional level before
functional limits can be considered meaningful (see Figure 4).
An example of this situation is the vibration of a turbine shaft. Vibration is caused by imbalances in the turbine
due to, for example, straightness deviations in the axis of the turbine shaft, roundness deviations of the turbine
shaft and variation in the weight of the fan blades. As the vibration level increases, the noise increases and
the life of the turbine decreases. The design criteria for the turbine include a requirement for minimum life. It is
impossible to manufacture a turbine with no vibration and the manufacturing cost generally goes up as
tolerances are reduced to limit vibration, so the design is based on an acceptable level of vibration that leads
to an acceptable life span. This acceptable level of vibration defines the X % workpiece functional level in
Figure 4. Specifications for the workpieces that make up the turbine can be derived from this minimum
acceptable functional level.
A
100 %
X %
C
0 %
LFL UFL
B

Key
A workpiece characteristic functional level LFL lower functional limit
B characteristic value UFL upper functional limit
C workpiece conforms
NOTE A minimum functional level of X % is determined and the functional limit is determined as the point where the
function degrades beyond this value.
Figure 4 — One-sided case with defined minimum acceptable functional level
4 © ISO 2010 – All rights reserved

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SIST-TS CEN ISO/TS 14253-4:2014
ISO/TS 14253-4:2010(E)
A
I
II
100 %
III
F1 %
F2 %
F3 %
C
0 %
B
FL=UFL2 UFL1 UFL3

Key
A workpiece characteristic functional level
B characteristic value
C workpiece conforms
I function 1
II function 2
III function 3
FL functional limit
UFL upper functional limit
Figure 5 — A characteristic value determines the functional level for three functions
Figure 5 shows the situation where one characteristic value determines the functional level for three functions.
Each function has a minimum acceptable functional level F1, F2 or F3. These minimum acceptable functional
levels each determine an upper functional limit for t
...