Title: On the economic-statistical design of control charts constrained by the inspection workstation configuration

Authors: Giovanni Celano

Addresses: Dipartimento di Ingegneria Industriale e Meccanica, University of Catania, Viale Andrea Doria 6, 95125 – Catania, Italy

Abstract: A key issue for the use of control charts in a manufacturing process is the selection of their design parameters. At the moment of chart design, it is important to consider the inspection resources available at the workstation and the process operating parameters, which can strongly constrain the search for optimal chart design parameters. In this paper, the constrained economic-statistical designs of EWMA and Shewhart charts monitoring the sample mean are compared: the SPC inspection activities are locally self-managed by a worker demanded also to perform the manufacturing activities at the workstation. The shift to the out-of-control condition for the monitored quality characteristic is assumed as a random variable. A benchmark of 64 process scenarios has been generated to investigate the influence of several process operating parameters and workstation configuration. Finally, the accuracy of the expected inspection cost estimation has been computed for several distributions fitting the random shift behaviour.

Keywords: statistical quality control; SQC; control charts; economic design; costs; constrained optimisation; resources; workstation configuration; stochastic shift; control chart design; economic-statistical design; EWMA charts; Shewhart charts; process monitoring; statistical process control; SPC.

DOI: 10.1504/IJQET.2010.034610

International Journal of Quality Engineering and Technology, 2010 Vol.1 No.3, pp.231 - 252

Published online: 13 Aug 2010 *

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