Conformity and statistical tolerancing

Statistical tolerancing was first proposed by Shewhart (Economic Control of Quality of Manufactured Product, (1931) reprinted 1980 by ASQC), in spite of this long history, its use remains moderate. One of the probable reasons for this low utilization is undoubtedly the difficulty for designers to an...

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Main Authors: Leblond Laurent, Pillet Maurice
Format: Article
Language:English
Published: EDP Sciences 2018-01-01
Series:International Journal of Metrology and Quality Engineering
Subjects:
Online Access:https://doi.org/10.1051/ijmqe/2017023
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author Leblond Laurent
Pillet Maurice
author_facet Leblond Laurent
Pillet Maurice
author_sort Leblond Laurent
collection DOAJ
description Statistical tolerancing was first proposed by Shewhart (Economic Control of Quality of Manufactured Product, (1931) reprinted 1980 by ASQC), in spite of this long history, its use remains moderate. One of the probable reasons for this low utilization is undoubtedly the difficulty for designers to anticipate the risks of this approach. The arithmetic tolerance (worst case) allows a simple interpretation: conformity is defined by the presence of the characteristic in an interval. Statistical tolerancing is more complex in its definition. An interval is not sufficient to define the conformance. To justify the statistical tolerancing formula used by designers, a tolerance interval should be interpreted as the interval where most of the parts produced should probably be located. This tolerance is justified by considering a conformity criterion of the parts guaranteeing low offsets on the latter characteristics. Unlike traditional arithmetic tolerancing, statistical tolerancing requires a sustained exchange of information between design and manufacture to be used safely. This paper proposes a formal definition of the conformity, which we apply successively to the quadratic and arithmetic tolerancing. We introduce a concept of concavity, which helps us to demonstrate the link between tolerancing approach and conformity. We use this concept to demonstrate the various acceptable propositions of statistical tolerancing (in the space decentring, dispersion).
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spelling doaj.art-1264110ff1e34f6fb3bac1557bfff3ef2022-12-21T20:05:49ZengEDP SciencesInternational Journal of Metrology and Quality Engineering2107-68472018-01-019110.1051/ijmqe/2017023ijmqe170032Conformity and statistical tolerancingLeblond LaurentPillet MauriceStatistical tolerancing was first proposed by Shewhart (Economic Control of Quality of Manufactured Product, (1931) reprinted 1980 by ASQC), in spite of this long history, its use remains moderate. One of the probable reasons for this low utilization is undoubtedly the difficulty for designers to anticipate the risks of this approach. The arithmetic tolerance (worst case) allows a simple interpretation: conformity is defined by the presence of the characteristic in an interval. Statistical tolerancing is more complex in its definition. An interval is not sufficient to define the conformance. To justify the statistical tolerancing formula used by designers, a tolerance interval should be interpreted as the interval where most of the parts produced should probably be located. This tolerance is justified by considering a conformity criterion of the parts guaranteeing low offsets on the latter characteristics. Unlike traditional arithmetic tolerancing, statistical tolerancing requires a sustained exchange of information between design and manufacture to be used safely. This paper proposes a formal definition of the conformity, which we apply successively to the quadratic and arithmetic tolerancing. We introduce a concept of concavity, which helps us to demonstrate the link between tolerancing approach and conformity. We use this concept to demonstrate the various acceptable propositions of statistical tolerancing (in the space decentring, dispersion).https://doi.org/10.1051/ijmqe/2017023conformity principlestatistical tolerancingrobust engineering
spellingShingle Leblond Laurent
Pillet Maurice
Conformity and statistical tolerancing
International Journal of Metrology and Quality Engineering
conformity principle
statistical tolerancing
robust engineering
title Conformity and statistical tolerancing
title_full Conformity and statistical tolerancing
title_fullStr Conformity and statistical tolerancing
title_full_unstemmed Conformity and statistical tolerancing
title_short Conformity and statistical tolerancing
title_sort conformity and statistical tolerancing
topic conformity principle
statistical tolerancing
robust engineering
url https://doi.org/10.1051/ijmqe/2017023
work_keys_str_mv AT leblondlaurent conformityandstatisticaltolerancing
AT pilletmaurice conformityandstatisticaltolerancing