Investigation of Dynamic Balance Process to Obtain Fine Powder by Plasma Rotating Electrode Process (PREP) Method

Due to the increasing demand for high-precision products in metal additive manufacturing, such as powder bed fusion, there is growing expectation for high-quality fine powders produced by the Plasma Rotating Electrode Process (PREP) method. However, the PREP method currently faces a bottleneck due to its low acquisition rate of fine powders below 50 μm. In this study, we analyzed the generation and control of molten layers in PREP and their relationship with centrifugal force, aiming for size reduction. Through experiments using SUS316L and Ti6Al4V alloys, we demonstrated that process parameters such as material diameter, melting current, and cooling gas could control powder size. A significant increase in the acquisition rate of fine powders with an average particle size below 40 μm was observed using a production-scale PREP apparatus with specific parameters. Furthermore, we found that the gas cooling mechanism plays a crucial role in controlling parameters like the melting temperature of the molten layer.