Economic design of EWMA control chart using quality cost model based on ARL

Statistical control charts have been widely used in manufacturing industry. The average run length (ARL) is a dominating measure of control chart performance. This paper presents an economic designing scheme of exponentially weighted moving average (EWMA) control chart. In this paper, a cost model of quality cycle is constructed. Then, the scheme of applying response surface methodology (RSM) to search the optimal set of EWMA parameters is presented. When quality cost given by the cost model is reduced to local minimum point, if satisfied, stop searching and the certain parameters set is found. A numerical case is used to illustrate the analysis procedure, and a sensitivity analysis is done to give a perspective of how the changes of system parameters affect the final results.