Application of Six Sigma Method to Reduce Defects in Green Sand Casting Process: A Case Study

Abstract

Six Sigma is statistical and scientific methods to reduce the defect rates and achieve improved quality. A case study carried out for a green sand casting manufacturing industry. Here Six Sigma methodology is used for the part: Transmission Case. DMAIC (Define?Measure?Analyse?Improve?Control) methodology along with Taguchi method is used to minimize the defects in the Transmission Case. The major tools used in this work are the project charter, process map and cause-and-effect diagram. Use of design of experiments (DOE) and analysis of variance (ANOVA) techniques are combined to determine statistically the correlation of defects with the mould hardness, green strength, and pouring rate also to find their optimum values needed to reduce/eliminate the defects. The experimental results were statistically analyzed and modelled through Taguchi analysis. Based on the findings, the optimized process parameters are taken for experiment and better performance obtained in the production process was confirmed. The comparison between the existing and the proposed process has been attempted in this paper and the results have been discussed in detail.