Prioritizing processes in initial implementation of statistical process control

A production process composed of tens or even hundreds of subprocesses is a common phenomenon in industry. Each of the subprocesses contributes to various aspects of product quality. Ideally, a control chart can be set up on every subprocess to guarantee the quality of the final product. This is not practical however, because of limited human and economic resources, and the management has to decide which subprocesses are to be given higher priorities. In this paper, for the purpose of prioritizing processes in complicated production systems for implementing statistical process control (SPC) schemes, preliminary selection based on statistical and technical criticality of processes is discussed. An analytic hierarchy process approach based on pair-wise comparisons between several factors in deciding the relative criticality of the processes in a hierarchy structure is then studied. The approach can be used in management decision making in planning for SPC implementation. A case study is presented to illustrate the methodology.