Application Of Six Sigma Management In The Quality Improvement Of Steel Welding Cylinders Manufactured By T Company

This thesis mainly studies the application of Six Sigma management ideas and management tools in the quality improvement of steel welded gas cylinders.Steel welded gas cylinders are a type of pressure vessel and special equipment which have extremely strict quality requirements.The quality of welding seam is directly related to the quality of steel cylinders.The main problem currently faced by T Company is that the hydraulic pressure test of steel welded cylinders has a low once pass qualification rate,which wastes time and materials to repair unqualified products and resulting in low production efficiency.In this situation,the Six Sigma management method was introduced.Therefore,how to use the Six Sigma quality management method to analyze and solve the problem of low once pass qualification rate of cylinder water pressure in T Company is the main research direction of this thesis.First,the thesis introduces the research background and current status of quality management of T Company,including quality management system,process,organizational structure and product quality improvement which are urgently needed.According to Six Sigma's DMAIC process thought;firstly we define the main quality problems are caused by welding which needs to be solved.Second,the relevant quality management tools are used to determine the main influencing factors of welding defects.Third,use Minitab software for data analysis,and carry out the experimental design(DOE)by T Company team.Finally,through the experiment,we will obtain the optimal welding parameter model configuration for effectively reducing the welding defects which can be applied in practice.Meanwhile,this welding qualification once pass rate data should be compared with the pre-improvement data to confirm the improvement effect.The significantly enhance of the improvement effect proves the validity of establishing the welding process parameter model as well as finding the direction of improvement of T Company quality management problems.The optimization scheme of quality management system,technology and procedure were formulated.Through the optimization of DMAIC process,T Company's product quality has been greatly improved,and a quality management system based on process control has been formed.In the end,the thesis summarizes the difficulties and shortcomings of the implementation of the Six Sigma management method,analyses the good changes brought by the Six Sigma method for quality management,and has prospect of the Six Sigma method that it will gets more applications in The future.Through the research in this thesis,the key quality management point of T Company has changed from product final inspection to process control.It has established a continuous improvement of quality management policy,and set up an optimized process parameter configuration model of submerged arc automatic welding for the steel welded gas cylinders.The purpose of this research has achieved.