Case study The application of Six Sigma to Process Improvement
Introduction
As requested in the quality homework, an article “Application of Six Sigma Methodology to Reduce Defects of a Grinding Process” [1] was studied. In the case from this article, an Indian automotive company was suffering from a high rejection rate for a certain piece (distance piece) in a component (fuel injector), which requires precise fine grinding to ensure good functioning of the injector. Due to the large amount of production rate of the pieces, it’s not practical to carry out 100% inspection. However the rejection rate was very high and the piece played a critical role in the whole component, thus it is an urgent task for the project managers to solve this problem by eliminating the defects rate.
Describing the improvement project
Purpose
With an expectation to reduce the defects rate as stated in the above problem, many attempts were made for the above problem by using different methodologies, but the results were all unsuccessful. Six-Sigma method was introduced for solving this problem and thus improving the productivity. DMAIC was presented to show how Six Sigma methodology worked. During these steps, many methods were used for detailed information such as DOE, Control Charts, Pareto diagram, interaction plots and the cause and effect diagram.
Results
After the application of Six Sigma, the company received a significant improvement in this grinding process, with the rejection rate of the distance piece reduced from 16.6% to 1.19% and the sigma level improved from 2.47 to 3.76. The DMAIC methodology had a significant financial impact on the profits of the company, with an annualized saving for this process of 2.4 million dollars. The results were very satisfying and the management was encouraged to make the decision to implement Six Sigma methodology for other processes.