Six Sigma Improvement For Appearance Defect Of Cylinder Block

Engine CA4CA1is1.3L gasoline engine, which designed by FAW technology center tomeet the demand for powertrain independent brand economy cars.It is produced in tianjinFAW xiali automobile co., internal combustion engine branch. However, when the enginecylinder blank casting rejection rate is high, especially the surface defects, and the body ofthree cylinders’ is an average of around1.8%, compared to the surface defects of scrap rateCA4GA1cylinder surface defects in the whole year of2012rejection rate is as high as13.26%, which becomes the main bottleneck of capacity affects the casting quality andproductivity.For high CA4GA1engine block casting defects, according to the six sigmamanagement process model, and to establish a standardized problem improvement methods,mainly through the following aspects:1. In the define phase, according to departmental strategic planning, combined with thesurface of the engine cylinder blank casting rejection rate is high, determine to do the project,and defines the scope of defects to be improved and team members.2.In the measurement phase, analyze the stability of the measurement system of thehardness of sand mould, the pouring speed and sand core loi to ensure the authenticity andvalidity of measurement results. Through the analysis to determine potential failure modes ofrapid improvement projects, and carries on the improvement.3.During the analysis phase, using statistical methods and tools to find out defects onthe surface of a cylinder block casting crucial key information,use of statistical tools toanalyze the problem such as adhering sand, hole, sand hole. Through collecting the data todetermine the relationship between each variable factor in the process and determine theimprovement direction. At this stage to determine the process how good or how bad the current performance, and identify possible root cause of quality variation. Data analysis cananalyze the basic properties and behavior of the process, and in a period of time cycle showability and stability of the process.4.In the improve phase, use regression analysis and response surface design method toimprove the factor according to conclusion on the root cause of the casting defects inanalyzing the phase.5.In the control phase, to control the improved results and standardized the related files,which ensure the future process under control and ensure the stability of the process.