Quality improvement by reducing variation: a case study

This article describes a systematic approach for solving a problem of high rejection and rework due to variation in the machining process. Two critical characteristics of a component under study were identified by risk analysis. The process capability of these characteristics was calculated and found to be very low. For improving the process capability, a step-by-step method was adopted by applying several statistical and quality tools, such as multivari chart, cause-and-effect diagram, gauge repeatability and reproducibility, design of experiments etc. After reducing the variation through continuous process improvements, the process capability has improved drastically.