Understanding powder degradation in metal additive manufacturing to allow the upcycling of recycled powders

Abstract

To ensure the financial viability of powder-based additive manufacturing technologies, the recycling of powders is common practice. This paper shows the lifecycle of metal powder in additive manufacturing, investigating powder manufacture, powder usage, mechanisms of powder degradation and the usage of end-of-life powder. Degradation of powders resulting from repeated reuses was found to be a widespread problem; components produced from heavily reused powders are typically of a lower quality, eventually rendering the powder unusable in additive manufacturing. Powder degradation was found to be dependent on many variables, preventing the identification of a definitive end-of-life point for powders. The most accurate method of determining powder quality was found to be the production and analysis of components using these powders. Uses for degraded powder had not been previously identified in literature, warranting the investigation of potential solutions to prevent powder waste. Amongst other waste-reducing solutions, plasma spheroidisation was identified as a promising method to avoid powder disposal for approximately 12.5% of produced powders, creating particles similar to virgin powder from end-of-life powder. Returning end-of-life powders to the supplier for upcycling may be the only financially viable solution to reduce waste within the industry. The compilation of research within this paper aims to enable users of additive manufacturing to conduct further research and development into powder upcycling.

Evaluation of Inconel 718 Metallic Powder to Optimize the Reuse of Powder and to Improve the Performance and Sustainability of the Laser Powder Bed Fusion (LPBF) Process

“…The powder that is not used to produce parts should be mixed before each process using a system- and material-specific virgin-to-used powder ratio [ 6 ]. Metal PBF, however, has a high powder recyclability, as metals are characterized by a slower degradation during the PBF process [ 7 , 8 , 9 ]. Nevertheless, the changes that occur in metal powders during their multiple reuses in the LPBF process should not be underestimated.…”

Topological, Mechanical and Biological Properties of Ti6Al4V Scaffolds for Bone Tissue Regeneration Fabricated with Reused Powders via Electron Beam Melting

“…In particular, they proposed material feedstock recycling as the first step in cost reduction. Material feedstock in EBM processes can affect up to 31% of the cost of built parts [ 16 ]. Therefore, recycling Ti6Al4V metal powder represents an affordable solution to reduce waste and save costs [ 17 ].…”

Powder Bed Fusion Additive Manufacturing Using Critical Raw Materials: A Review

“…Powder recyclability is a crucial parameter of powder lifecycle and overall manufacturing efficiency. In metal-based processes (PBF, LENS) the microstructure of the virgin (not recycled) powder has a certain tendency to change due to repetitive reuse and recycling [ 14 , 166 , 167 ]. The flowability and powder morphology can change because of thermal cycling during processing and mechanical impacts during layer deposition, powder recovery, and sifting.…”