Optimizing Process Control Parameters

Presents a modification of Saniga′s model for joint economic design of process control parameters, i.e. sample size, sampling frequency and critical regions for X and R charts. The objective is to minimize the total system cost, which consists of the cost of sampling and charting, the cost of searching for and correcting the assignable causes of quality variation, the cost of downtime or production loss, and the cost of producing defective items which have to be reworked or scrapped. The modified model has been applied to control the internal profile milling of steam‐turbine blades. Highlights the saving potential of the optimum design of process control parameters.