Chart allocation strategy for serial–parallel multistage manufacturing processes with multiple faults

Abstract

Although statistical process control (SPC) charts have been used for multistage manufacturing process quality monitoring for years, how to effectively allocate conventional SPC charts appropriately in a serial–parallel multistage processes has not been thoroughly studied. In this article, aiming to minimize the expected overall quality cost, we use the linear state-space model to model multistage processes and propose a strategy to properly allocate control charts in serial–parallel multistage manufacturing processes by considering the interrelationship information between stages and the simultaneous occurrences of multiple faults at different workstations. Based on the proposed chart allocation strategy, we are able to make rational chart allocation decisions to achieve quicker detection capability over the whole potential fault set. A hood assembly example is used to demonstrate the applications of the chart allocation strategy.