Research On The Quality Improvement Of Jacket Core Of Engine Cylinder Block Based On DMAIC Process

With various challenges have to be faced,automotive manufacturers begin to focus on costs reduction and processes improvement to help enterprises survive.As one of the largest vehicle manufacturers in China,SVW always regards high-quality products as the core competitiveness,therefore,it will has representative significance to other automobile manufacturing companies.SVW launched the C model project in 2018,but the high defect rate of the water jacket part of the engine cylinder block poses a severe challenge.So SVW urgently needs to improve the quality of this part to reduce the defect rate of the product.This thesis adopts DMAIC process of Six Sigma to improve jacket core quality.At first,after analyzing SVW quality management system and jacket core production process with SIPOC analysis,the main defects are defined as follows:insufficient hardness of sand mold,excessive burning reduction of sand core and insufficient anti-rubbing strength of coating.Furthermore,the measurement system are evaluated by MSA tools and process capability are defined.Thirdly,preliminary improvement of water jacket core quality is carried out through C&E analysis and FMEA.Then,the key factors are further recongnized by hypothesis testing and have been analyzed by DOE design and RSM analysis.Finally,the standardized control methods are carried out to keep jacket core quality improvements.Through DMAIC implement,the quality of water jacket core has been successfully improved,as the defect rate reduced from 13.6% to 2.25%,and Six Sigma level has increased from 2.6 to 3.5 with 1,352,55 RMB money saved annually.Through this concrete practice,the quality management level of SVW company has improved and this research results can be applied to other manufacturing industries.