Wire Arc Additive Manufacturing of Ti-6Al-4V components: the effects of the deposition rate on the cradle-to-gate economic and environmental performance

Wire Arc Additive Manufacturing (WAAM) is a direct energy deposition process based on a wire-shaped metal feedstock which is melted by means of an electric arc to produce and/or repair components in a layer-wise manner. WAAM has shown to be suitable for producing large components, in particular those with a near-to-net shape, at relatively high productivity levels. The aim of this work has been to assess the effects of the WAAM deposition rate on economic and environmental sustainability metrics. A life cycle assessment has been performed under cradle-to-gate system boundaries. Three components, with different geometrical characteristics (i.e., dimensions, masses, and solid-to-cavity ratios) and made of Ti-6Al-4V, have been considered as case studies. The effects of different deposition rates have been evaluated on the Cumulative Energy Demand, CO2 emissions, manufacturing times and costs. The conventional manufacturing route for the production of the same components, that is, machining from massive workpieces, has been considered as a benchmark for a process performance comparison. The results show that an increase in the deposition rate determines a significant reduction (up to 25%, on average) in the production time and, consequently, in the manufacturing costs.