Statistical Process Control ― Returning to Origins for a New Development ―

Abstract

　This paper discusses the dual aspect of process capability information and the role of the Shewhart control chart as a control chart for process control ( type 2 control chart ), by exploring their essence through a return to the origin.
　The dual aspect of process capability information refers to the idea that the variation in assurance characteristics for process downstream is Process Performance, and the ability to create Process Performance is Process Capability. It is proposed that process quality be assured through “ Process Performance backed by Process Capability. ”
　The role of control charts for process control is to prove the effect of intentional intervention, namely standardization that creates a controlled state, during the phase of routine mass production.Then it is important to select control characteristics that are conscious of the need to know the process. The anomaly signaling from a control chart for management serves as a clue for transitioning to a control chart for process analysis. This phase should be located as phase 3 in road map of control chart in SPC.