Chart allocation strategy for serial-parallel multistage manufacturing processes

The application of Statistical Process Control (SPC) to multistage manufacturing process has received considerable attention recently. How to effectively allocate conventional SPC charts in a serial multistage environment to monitor the process quality has not been thoroughly studied. This article adopts the approach of a linear state space model to describe multistage processes and proposes a strategy to properly allocate control charts in serial parallel-multistage manufacturing processes by considering the interrelationship information between stages. Based on the proposed chart allocation strategy it proves possible to make rational chart allocation decisions to achieve a quicker detection capability over the whole potential fault set. A hood assembly example is used to demonstrate the applications of the chart allocation strategy. Extensions are also discussed.