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

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 wide-spread 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. Crown Copyright (c) 2020 Published by Elsevier Ltd. All rights reserved.