Powder reuse has been an integral part of beam-based additive manufacturing in recent years. Tracking the quality change of the reused powder is essential for the end users. Mapping this track record can lead to defining some cut-off and threshold limits for powder parameters according to the required mechanical properties of the final part.

In this research, the physical and chemical properties of the reused powder were assessed against the virgin powder. The waste powder after each process was sieved for further runs. Powder flowability before and after reuse was measured using the rotating drum test. Particle size distribution and morphological classifications were also assessed using static image analysis. In the absence of a global standard for defining the morphological group classifications such as circular, satellited, and elongated particles, the boundaries of shape descriptors from a previous study, presented at World PM 2022 [1], were used in this study. In addition to the physical properties, the chemical composition of the powder was analysed using X-ray fluorescence. A series of SEM images were taken to evaluate the surface characteristics of the virgin and reused powder. The full characterisation data was processed, and each parameter was plotted against the number of reuses. The trend of quality change was then explored and discussed.

The Materials Processing Institute aims to develop a platform including versatile methodologies to evaluate powder for recycling and reuse. In this study, the track record of powder characterisation, termed powder history, that maps the actual capability of the metal powder for future reuse was captured. It assists the end users to estimate the lifetime of their material. This approach proposes using a characterisation data bank to predict the performance of reused powder for laser powder bed fusion process.

References

[1] E, Rahimi; A. Hunt; X. Hao World PM, 2022, European Powder Metallurgy Association (EPMA), Session 60.