Int. J. Metrol. Qual. Eng.
Volume 4, Number 2, 2013
|Page(s)||71 - 80|
|Published online||07 November 2013|
Testing capability indices for one-sided processes with measurement errors
Laboratory of Applied Mathematics, CNRS UMR 5142 IUT de Bayonne,
Université de Pau et des Pays de l’Adour, 17 place Paul Bert, 64100
⋆ Correspondence: firstname.lastname@example.org
Received: 4 September 2012
Accepted: 10 July 2013
In the manufacturing industry, many product characteristics are of one-sided tolerances. The process capability indices Cpu (u, v) and Cpl (u, v) can be used to measure process performance. Most research work related to capability indices assumes no gauge measurement errors. This assumption insufficiently reflects real situations even when advanced measuring instruments are used. In this paper we show that using a critical value without taking into account these errors, severely underestimates the α-risk which causes a less accurate testing capacity. In order to improve the results we suggest the use of an adjusted critical value, and we give a Maple program to get it. An example in a polymer granulates manufactory is presented to illustrate this approach.
Key words: Process capability indices / gauge measurement error / one-sided tolerance process / critical value / power test
© EDP Sciences 2013
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