Improving failure analysis efficiency by combining FTA and FMEA in a recursive manner

When designing a maintenance programme for a capital good, especially a new one, it is of key importance to accurately understand its failure behaviour. Failure mode and effects analysis (FMEA) and fault tree analysis (FTA) are two commonly used methods for failure analysis. FMEA is a bottom-up method that is less structured and requires more expert knowledge than FTA, which is a top-down method. Both methods are time-consuming when applied thoroughly, which is why in many cases, they are not applied at all. We propose a method in which both are used in a recursive manner: First, a system level FTA is performed, which results in a set of failure modes. Using FMEA, the criticality of the failure modes is assessed in order to select only the critical system level failure modes. For each of those, a function level FTA is performed, followed by an FMEA. Finally, a component level FTA and FMEA are performed on the critical function level failure modes. We apply our method to a recently developed additive manufacturing system for metal printing, the MetalFAB1 of Additive Industries (AI), and find that the engineers at AI consider the method to be efficient and effective.