Cradle-to-gate life cycle assessment: a comparison of polymer and metal-based powder bed fusion for the production of a robot end-effector with internal conformal channels

Abstract

Diferent industries are adopting additive manufacturing (AM) technologies to produce complex designs with minimum material wastage. The sustainability assessment of AM technologies is therefore essential to address the current environmental challenges. This research aims to compare the environmental impacts of diferent raw materials used for the production of a robot end-efector with internal conformal channels via powder bed fusion (PBF) and provide a framework to assess the sustainability of polymer, metal, and composite-based materials selected for this technology. A life cycle assessment (LCA) was performed comparing the production of a robot end-efector using three diferent raw materials, i.e., Polyamide 12 (PA12), aluminum alloy powder AlSi10Mg, and a composite of PA12 and graphene nanoplatelets (to induce electrostaticdissipative properties for attaining functionality of picking and placing printed circuit boards) via PBF technology. Selective laser sintering (SLS) and direct metal laser sintering (DMLS) processes were considered to produce the robot end-efector. The scope was cradle-to-gate, including raw material extraction, transportation, transformation during manufacturing, and corresponding energy utilization. Environmental impact assessment categories are divided into air, water, and land emissions. These include global warming (GW), stratospheric ozone depletion (SOD), fne particulate matter formation (FPMF), water consumption (WC), freshwater ecotoxicity (FWT), freshwater eutrophication (FWE), fossil resource scarcity (FRS), land use (LU), terrestrial acidifcation (TA), and terrestrial ecotoxicity (TE). Three diferent raw materials used to produce robot end-efectors were compared using the ReCiPe Midpoint (H) impact assessment methodology. According to the results, the production of the robot end-efector using PA12 had the lowest environmental impact. Electricity consumption during the PBF and the production of raw materials were the overall major contributors to the selected environmental impact categories. A generic framework to assess the environmental performance of materials used for PBF is proposed. A detailed cradle-togate LCA is performed to highlight the environmental hotspots of PBF technology and ways to improve the environmental performance of AM in general.