Lean six-sigma: Panacea to reduce rejection in gear manufacturing industry

Abstract

This paper has covered the elimination of process variation to remove the wastages in the gear manufacturing industry. The well-known DMAIC (Define-Measure-Analyze-Improvement-Control) approach, which is the part of Six Sigma was used to decrease process variability, which contributes to a decrease the waste, thus improves total business efficiency. DMAIC methodology has been adopted for this research work in which various tools have been used, such as SIPOC (Supplier, Input, Process, Output, Customer), Pareto analysis, MSA (Measurement System Analysis), SPC (Statistical Process Control), Root & Cause analysis. A Bull gear product of the Company was selected for the improvement as this product has the highest rate of rejection. The variation in Measurement over Teeth (MOT) and Pitch circle diameter (PCD) were two defects which had a major contribution to rejection. When the framework was successfully deployed, Bull Gear rejection level was reduced from 10641.08 to 13193.21 ppm (part per million) and the sigma level increased from 4.37 to 4.81 with the sigma shift. These results demonstrated the impact of the lean six-sigma initiative at the gear company, which has operational efficiency and improved consistency to improve business performance and accommodate customer’s needs.