Calculating RPN Index in FMEA Table by Fuzzy Expert Systems

FMEA is a methodology to evaluate a system, design, process or service for possible ways in which failures can occur. The FMEA team often demonstrates different opinions and these different types of opinions are very difficult to incorporate into the FMEA by the traditional risk priority number model. Also in conventional FMEA, if the severity index of a failure is high, the failure mode should be considered for setting corrective plan even though its RPN is not high. In this practice for each parameter namely Occurrence, Severity and Detectivity, a fuzzy set was defined. The contribution of this paper is in considering the opinion of each member of the FMEA team. These opinions were considered simultaneously with weights that given to each individual due to their skill and experience. To consider the opinion of the costumer, the costumer's idea was considered for each of the FMEA's parameters. Then by using a Multi Input Single Output (MISO) fuzzy expert system, Risk Priority Number index was calculated. Finally, these new fuzzy FMEA methods was implemented for analyzing failures of engines' production line in Peugeot 206 engines' shop No.3 in Iran Khodro Company.