Recycling of used metal powder for additive manufacturing via vibratory disk milling

Metal additive manufacturing produces less material waste than traditional manufacturing. However, metal powder waste is difficult to recycle compared to the bulk scrap of the same chemistry generated from conventional processes. The powdered material can have a more significant deteriorating impact on the environment. As one of the recycling strategies, ball milling of waste powder has been extensively studied; however, this method can take up to 48 h and typically produces plate-like particles, which are not ideal for many additive manufacturing methods. This study explored vibratory disk milling of used 316L stainless steel powder as a faster recycling method. It was found that the average particle size could be reduced by an average of 24 μ m within a 1 h milling time frame, while retaining a majority of spherical particles. Along with particle size, this study also examined the morphology, chemistry, and printability of the disk-milled powders. Based on these observations, a plausible milling mechanism was proposed. These results indicated that vibratory disk milling provides a time-efficient pathway for recycling the powder into usable feedstock for additive manufacturing.