Machining Center Quasi-full Life Cycle FMECA Study For Key Production Stage Characteristics

Machining center as the most widely used type of CNC machine tool,in recent years has made great progress,but domestic machining centers and Germany,Japan and other countries still have a certain gap,one of the important reasons is the low reliability of domestic machining centers.Because the design,selection,manufacturing and assembly of the components of the machining center will directly affect the reliability of the whole machine,the design stage is the foundation stage of the reliability of the machining center,the manufacturing stage is the guarantee stage of the reliability of the machining center,the use stage is the maintenance stage of the reliability of the machining center,they are a complete process,in order to improve the reliability of the machining center,should not only focus on the reliability of a single stage,but try to start from the entire life cycle,Grasping every critical stage that can improve reliability can only lay a solid foundation for the high reliability of machining centers.Therefore,it is of great significance to study the FMECA method of machining centers from the quasi-full life cycle to improve the reliability of machining centers.This paper through the enterprise site tracking obtained fault data,the use of active prevention methods to improve the level of reliability,in the design stage to improve the inherent reliability of the machining center,in the manufacturing stage to ensure the inherent reliability level of the machining center design stage,and then in the use of the stage to greatly improve the reliability of the whole machine,but also through the use of the FMECA analysis of the design stage,manufacturing stage to provide data support,so that the improvement of reliability into a virtuous circle,the specific research content is as follows:(1)The FMECA analysis method commonly used in the traditional design stage is introduced,and the efficiency value of the potential failure mode is calculated by combining the cognitive optimal worst method and the data envelopment analysis method to calculate the efficiency value of the potential failure mode by taking into account the problem that the evaluation factor is small and the evaluation criteria are general,and the risk factor evaluation index is increased by refining the risk factor evaluation index.This paper proposes an RPN calculation method combining risk factors,weights and efficiency values to determine the risk ranking,provide a basis for whether to implement design improvement measures,and verify the feasibility of the proposed method.(2)Comprehensively consider the price,quality,supply and service of outsourced parts,and determine them as risk factors,and describe their meaning and scoring methods in detail.Using the method of combining the cognitive optimal worst method and the approximate ideal point ranking method,the selection scheme of outsourced outsourcing is sorted by the risk size,and the selection scheme with the highest reliability will overcome the traditional risk factor scoring method to obtain several of the same risk priority numbers,and the problem of risk size cannot be well distinguished.Taking the motor as an example,the simplicity and practicality of the method are verified.(3)The FMECA analysis method in the manufacturing stage is introduced,aiming at the problem that the probability of process failure is difficult to determine,comprehensively considering the process requirements and the probability of failure,and using the fuzzy interval method to determine the degree of occurrence of risk factors.The efficiency value of potential failure modes is evaluated by the data envelopment analysis method,and the traditional RPN is corrected,which solves the dilemma that the RPN in the traditional FMECA analysis is only the multiplication of risk factors but has no reasonable scientific basis,and the weak process is determined by the method,which verifies the feasibility of the method.(4)In view of the problems such as few FMECA analysis factors in the use stage and the interaction between the factors that are not considered,the network hierarchy method is used to determine the weights of each risk factor,and considering the maintainable type of the machining center,combined with the data envelopment analysis to obtain the efficiency values of each failure mode,a method for calculating the RPN is proposed,and FMECA analysis of the collected fault data is carried out with a certain type of machining center as an example,which verifies the feasibility of the method.