Environmental and safety aspects of AM metal powder recycling

Paper in proceeding, 2019

Repeated recirculation of powder in AM processes ultimately results in a powder with degraded properties. We firstly discuss this topic and describe an experiment designed to understand the mechanisms behind the degradation. Secondly, we perform yield analysis for build jobs on a SLM 125 at RISE IVF. Further on, we consider the required resources and estimate the emitted carbon dioxide equivalents (kgCO2eq) during production of the PBF-LB fraction of two gas atomized powders. The first powder is a tool steel alloy that emits 3.1 kgCO2eq/kg; the second powder is Hastelloy X (HX) that emits 24.2 kgCO2eq/kg. The HX powder, if degraded, is hence very desirable to recycle. Producing 1 kg of PBF-LB fraction from recycled HX material causes 5.7 kgCO2eq vs 24.2 from virgin sources. Finally, we review the health and safety aspects of recirculation and recycling of powder.