Multi-material Additive Manufacturing: Metal Powder Recycling via Sedimentation

Powder-based multi-material additive manufacturing (AM) enables arbitrary material composition in parts. This opens new freedom of design possibilities for high-performance components. During multi-material AM however, processed powders get mixed and occurring cross-contaminations can lead to inferior part quality. Therefore, mixed powders need to be separated during recycling. As fluids generally increase selectivity of many sorting processes, this study investigates the possibility to apply a well-established fluid media-based sorting processes to recycle metal AM powder mixtures: sedimentation. Sink rates of four different, commonly processed metal alloys are examined experimentally. Furthermore, influence of fluid media on powder quality is discussed. For this purpose, non-corrosive fluids are selected - volatile hydrocarbons being most suiting. Concluding, the applicability of sedimentation as multi-material powder recycling solution is evaluated.