Economic design of control chart for trended processes

Statistical control charts are widely used in manufacturing industry. However, for processes exhibiting certain trend pattern, which stems mainly from deteriorating elements such as power consumption or tool-wear, traditional control charts have to be interpreted differently. This paper addresses appropriate timing problem of making adjustment to such trended processes through economical design of its control chart. This extends the traditional study on economic design of control chart, which mainly focuses on the setting of control limits. An economic design model is developed and analytical results are presented. An application example is used to illustrate the decision-making and analysis procedure. © 2002 Elsevier Science B.V. All rights reserved.