| Product T as the control valve used for commercial vehicle braking process,the function of product T directly related to commercial vehicle running safety.So the internal quality requirement and quality control is very strictly,meanwhile,the cost of poor quality is very high.So the quality improvement of product T is very important for company business.In this lecture,the six sigma DMAIC method used for product T assembly FPY improvement on Z company.Firstly,further measure the product T assembly FPY and divide into detailed failure mode,find the top 80%failure mode is cavity 11 leak,cavity 43 leak and cavity 22 leak by pareto.And leak rate are precise after leak tester verified effective using MSA method.Secondly,considering principle of product T,use FTA method to identify potential causes for different leak points of cavity 11 leak,cavity 43 leak and cavity 22 leak.check actual leak points by water test,screen top 80%leak points and further survey in following research.Main leak points for cavity 11 leak is point 2/3/4,main leak points for cavity 43 leak is point 5/6,main leak points for cavity 22 leak is point 12/13/15/16.(1)Cavity 11 leak:obvious failure mode found during water test for leak points 2/3/4,raise quick improve proposals to reduce defects of the plastic pistons and O rings.(2)Cavity 43 leak:obvious failure mode found during water test for leak points 5,raise quick improve proposals to reduce casting defect of Al body;for leak point 6,find depth of piston is key factor by using components search method and regression analysis.(3)Cavity 22 leak:obvious failure mode found during water test for leak points 15,raise quick improve proposals to reduce casting defect of Al piston;for leak point 12,find O ring assemble method is key factor by using components search method/ANOVA;for leak point 13,find cutting fluid density/rotate speed/feed rate are key factors by using components search method/ANOVA/DOE;for leak point 16,find adjust screw assemble method is key factor by using components search method/ANOVA.Finally,specific improve actions and safeguard plan for each key factors.Company Z applied quality management tools and Six Sigma method successfully on product T assembly FPY improvement,and realize good improve effectiveness. |
