A Tool for Ensuring Consistent Occurrence Ranking in FMEAs

In the automotive industry, FMEA occurrence ranking is made to a standard such as SAE J1739. The SAE J1739 standard, as does other comparative standards, provides numerical probability criteria to aid ranking. Problems arise when the part or system under analysis is new, and there is no field data to estimate the probability of failure occurrence. Attempts to use qualitative verbal criteria or to go by the “feel” often result in inconsistency or large variability across and within FMEA projects. This paper presents a case study in which this problem was solved by the development of a tool that enables consistent – and efficient – FMEA occurrence rankings. The tool takes input from the user in the form of multiple-choice answers and calculates the final solution. The focus of this paper is the process and thinking behind the creation of this methodology – rather than justification of the tool itself – in the hopes that other automotive enterprises tackling the same issue may find ways to develop their own solutions.