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 bottomup 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.

In a selective laser melting process, it is common to reuse the powder in consecutive cycles of the route because it is more sustainable and cost effective. However, it is unknown whether reusing the material has an influence on the process. In this paper, Inconel 718, Ti6Al4V, AlSi10Mg and Scalmalloy are characterized to determine the impact of reusing powders on the additive manufacturing (AM) process under an argon high-purity atmosphere. Virgin powders were taken from the suppliers and compared to powders that had been used in the process for a long period of time with periodic 'rejuvenation'. A well-structured characterization procedure, combining many existing techniques, is proposed, determining changes in the morphology, composition (chemical and microstructure) and flowability. Clear differences between the virgin and used state are revealed by the characterizations; AlSi10Mg, appears to be the most sensitive to reuse with changes in particle size distribution and morphology, and with an increase in the oxygen content. The main contribution of this paper is providing insight into the effects of reuse for four commonly used AM powders, by means of a simple but well-structured method that links the particle feature characterization process to the flowability of metal AM powders. The provided insights enable enhanced decision-making on recycling and reuse of powder for specific AM processes.

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