| In recent years,Global trade frictions are increasingly aggravated,the COVID-19 pandemic is raging around the world,and the environmental and climate deterioration is becoming more and more significant.All of these factors have led to weak global economic growth and a great impact on global trade.Y Company’s main sales market of Nd2Fe14B magnetic steel products,in addition to the domestic,also spread across many countries and regions in Europe,America and Asia,its export trade will inevitably be affected.In addition,the country’s supervision of upstream rare earth raw materials tends to be more stringent,leading to the rise in raw material prices.At the same time,the production cost of downstream customers is generally rising,and the need to reduce the procurement cost of parts is more urgent,so as to push suppliers to reduce the manufacturing cost of products.In the face of domestic and foreign economic situation changes and the rise of manufacturing costs in the upstream and downstream of the industrial chain,Y company regards how to reduce cost of quality as one of the priority problems to be solved by the company.The product quality is guaranteed by the manufacturing process,so how to improve the process quality of the manufacturing process and then improve the qualified rate of the product has become the research focus of reducing the product manufacturing cost.Based on the principle of improving process quality,this paper selects representative S products for analysis.(1)Identify the type of product nonconformity.Firstly,the quality data of S products were counted to identify the main types of nonconformities,and then the size nonconformities were identified as key quality characteristics(CTQ)through the Pareto diagram.Secondly,the Pareto diagram is used to further analyze the dimensions of S product in three directions.Finally,the unqualified dimension of 90.5mm is determined as the priority for improvement,and the corresponding surface grinding process is the priority for analysis and improvement.(2)Determine the cause of size nonconformity.Firstly,the measurement system analysis(MSA)of the digital micrometer used in the surface grinding machine is carried out to determine the accuracy measurement requirements that can meet the dimensional tolerance of S products.Secondly,confirm the current situation of the surface grinding process capacity(Cpk).It was concluded that the current process capacity of the grinding process could not meet the requirement of Cpk≥1.33.Finally,in order to further determine the reason for the low process capacity of the surface grinding machine process,through the use of causal analysis diagram and Source of Variation(SOV),it is determined that the reason for the unqualified size is the large radial runout of the grinding wheel of the surface grinding machine and the poor flatness of the work table.(3)Develop improvement strategies.Firstly,the parameters of the surface grinding machine were adjusted to achieve the best working state,and the process capability of the surface grinding machine was re-verified.The verification results still could not meet the requirement of Cpk≥1.33.Secondly,considering the existing equipment and processing methods,verify the feasibility of processing S products by two double face grinders in series.Finally,identify the key process parameters of double face grinder by causal analysis diagram,and determine the optimal combination of equipment parameters by robust parameter design.The verification results showed that the processing capacity met the requirement of Cpk≥1.33.(4)Monitoring process stability.Follow up and confirm the improved process flow,monitor the size fluctuation with SPC,and confirm the process parameters with checklist.In this paper,by identifying the main quality problems of S product,making targeted improvement measures,improving the process ability to improve the process quality,effectively improving the qualified rate of products,and achieving the expected improvement effect. |
PDF Full Text Request