Application of group control charts for multiple parts manufacturing

Abstract

In many manufacturing processes, multiple identical parts are made in parallel during a single run. Different inspectors may inspect similar parts, and several assembly lines may produce similar products. These scenarios involve multiple stream processes, where a different set of control charts is traditionally required to monitor the performance of each stream over time. As the number of streams increases, applications become unrealistic. Group control charts offer a more viable alternative. This paper presents a review of group charting techniques and highlights recent developments. The paper presents a case study to demonstrate the steps to be followed in selecting among alternative charting techniques. It is hoped that this work guides future applications and encourages quality professionals to select charts better suited to their needs.