The Process capability study in Japan originated with DENSO Corporation when they awarded Deming Prize in 1961. Because they introduced and developed it companywide, they got significant improvement in both quality and cost. Process capability study is an activity to analyze causal relation between quality characteristic and 4M(Man, Machine, Material, Method) by comparing and investigating data in manufacturing processes with time series change and stratification. And, it is an activity to contribute to quality assurance and preventive maintenance by reflecting the results in standardization and process control in manufacturing processes. Moreover, process capability index, which is an evaluation standard of process capability, was developed in order to efficiently promote process capability study, since the use of SQC and instrumentation technology was indispensable. In this paper, I will explain the progress of how process capability study activities have significantly contributed to improving product quality in the automotive industry.
