An Improved FMEA Based On Interval Probability And Its Application In The Spark Plugs' Assembly Process Of B Company

Manufacturing is one of the pillar industries of the national economy and has a decisive position in economic and social development.However,due to the late start of chinese manufacturing industry and long-term pursuit of development speed,manufacturing technology is relatively backward.In addition,the production management methods of the enterprises are not perfect enough,so the product quality has not been significantly improved in the long run,which is at a disadvantage in the market competition.The high-quality development of manufacturing industry is inseparable from advanced production management technology.Among them,quality management is always the focus in the research of enterprise management technology.Scientific quality management technology is not only an important means for companies to improve product quality and reduce production costs,but also the key factor to obtain competitive advantages in the fierce market competition.The automobile industry is a representative industry of the manufacturing and a significant industry to improve product quality in China.Automobile manufacturing process is a complex systematic project which involves many parts.It is very difficult to control product quality in the industry,which restricts the development of chinese automobile industry to some extent.Based on the situation,to improve product quality,this paper takes the spark plugs of B automotive parts enterprise as the research object,and proposes a quality control FMEA method based on interval probability theory.First,this paper studies the assembly process of spark plugs,analyzes the current situation of quality control and the limitations of traditional quality control methods in assembly line of spark plugs.Second,based on the theories of FMEA,rough set and interval number,an improved FMEA method based on interval probability theory has been constructed.This method extends the single value of expert evaluation into interval numbers through rough set theory,which can reduce the subjectivity and ambiguity of expert evaluation.Meanwhile,when calculating risk evaluation indicators,it adopts the form of exponential RPN to improve some drawbacks of traditional FMEA,such as the duplicated numbers of RPN,the violation of measurement scale principle in the calculation of RPN and not considering the weight of the risk factors.In addition,when conducting the risk ranking process of failure modes,the comparison probability of different interval RPNs is considered as the ranking indicator,which can significantly reduce the loss of information during the risk assessment process and improves the accuracy of the FMEA analysis.Finally,the proposed method is applied in the quality improvement project of the spark plugs' assembly process in B company.The analysis results are compared with some existing methods,eg.the traditional FMEA,the fuzzy FMEA and the exponential FMEA to validate the effectiveness and reliability of the proposed method.Besides,we provide some improving advice for failure modes of different risk priorities.