The Research Of Six Sigma Method In The Improvement Of M Company's Product Quality

Automobile industry is an important pillar industry of the national economy.The overall development of our automobile industry is in good status,and has entered the stage of steady slow growth at a high annual volume.Along with higher expectation of quality product from end consumers,warranty claims and product recall have become a serious problem for manufacturers both on finance and reputation.It requires immediate action to improve the quality control level of automotive products.Opportunities and challenges coexist in automobile industry currently,six sigma method,as a breakthrough of the continuous improvement method,can help automobile manufacturers to enhance their capability of process control,continuously improve product quality,first pass yield rate,manufacturing efficiency and reduce quality cost.This paper introduced the case of improving pinion runout defect rate in M company by using DMAIC methodology,and studied how to effectively implement the six sigma management in a product quality improvement project.The practice of six sigma pinion runout improvement in M company includes project planning with project planning table,by using cause-effect diagram,brainstorming,the cross-functional team had worked together to find out the vital factors which contributes to part deformation from detailed process map.They had also performed MSA to ensure gage R&R meet expectation and analyzed process capability.Hypothesis test was used to analyze whether or not certain factors improvement helped with minimizing deformation.After I-MR control chart and box plot analysis of pinion deformation,DOE test was designed to understand impact of several major contributors to output.By using ANOVA.analyze main effect and interactive effect significance.By using Pareto chart and response optimizer,the team found out major contributors and optimized combination.The solution effectiveness was validated by failure rate reduction in I-MR control chart of small batch production.At last,M company six sigma team revised process control plan and continue using P chart to monitor effectiveness of improvement.Overall,by using six sigma methodology,this project achieved its goal of reducing pinion runout failure rate.By analyzing the practice of M company,this paper studied the challenges of implementing six sigma methodology in automobile manufactures.The implementation of specific project will benefit the establishment and enhancement of six sigma quality management culture.And it provides very effective way for manufactures to improve product quality.This paper could be a good reference to automobile manufactures of implementing six sigma quality management process.