JOINT DETERMINATION OF PRODUCTION QUANTITY, INSPECTION SCHEDULE, AND CONTROL CHART DESIGN

This paper presents a model for jointly determining an economic production quantity, inspection schedule and control chart design of an imperfect production process. The process is subject to the occurrence of a non-Markovian shock having an increasing failure rate. The product quality of the process is monitored under the surveillance of an xBAR-control chart. The objective is to determine the optimal control chart design parameters and production quantity so as to minimize the expected total cost (the quality control cost and the inventory control cost) per unit time. Both uniform and non-uniform inspection schemes are considered. For non-uniform inspection schemes, the length of the inspection intervals are regulated to regulated to maintain a constant integrated hazard rate over each inspection interval. Examples of Weibull shock models having increasing failure rates are provided. It is shown that the non-uniform and decreasing process inspection intervals scheme resulted in a lower cost than the uniform inspection scheme.