Thermoacoustic Consolidation of Metal Particles for Energy-Efficient Metal Powders Recycling in Metal Additive Manufacturing

Abstract

In laser powder bed fusion (LPBF) technology, approximately 20–30% of powder feedstock is stored after multiple cycles of sieving and reclaiming due to the deviation from standard particle geometry and size distribution. At present, there are no feasible ways to recycle these out-of-spec powders and they are being stored. This leads to storage-related issues and increases safety risks in manufacturing facilities. Here, we introduce an energy-efficient method to consolidate this hazardous metal waste into filament feedstock for repurposing without melting. In general, traditional production of wire feedstock is predominantly done using energy-intensive thermal melt-cast processes followed by mechanical drawing. The proposed technology compresses the multi-step process flow into a single-step technique of discrete-phase raw material consolidation and shaping into wire feedstocks using acoustic energy. This can bring about significant energy and cost savings in feedstock production and create a new route for reclaiming and repurposing of discrete-phase metal materials in production processes such as LPBF. In this work, we investigated the feasibility of utilizing low processing temperatures and power ultrasonics to consolidate out-of-spec metal powders. The effect of processing temperature and time on the porosity and microstructure of the consolidated samples has been studied. The results from this study will help us to develop a semi-continuous roll-forming technology to produce wire feedstocks for direct use in other additive manufacturing processes such as direct energy deposition or wire arc additive manufacturing.