Comparison of Wire Arc Additive Manufacturing and Subtractive Manufacturing Approaches from an Environmental and Economic Perspective

Wire arc additive manufacturing (WAAM) is a metal AM process that uses metal wire as feedstock and an electric arc to melt the feedstock wire. WAAM has gained attention in the industry due to its benefits like better material efficiency and higher deposition rates. However, WAAM needs post-processing operations like machining due to its poor surface finish. Therefore, the sustainability potential of WAAM can’t be presumed and needs to be proven quantitatively. Fewer studies that conduct an environmental or economic assessment of WAAM are present and do not comprehensively study the effect of post-processing on WAAM’s performance. Therefore, the main objective of this study is to carry out an integrated and quantitative environmental and economic assessment of the WAAM process, including the effect of its post-processing operation. A case study of a product: a marine propeller made by WAAM and CNC milling technologies is presented. It is observed that the WAAM approach causes a 60% lower environmental impact compared to CNC milling. However, the WAAM approach is found to be slightly more cost-efficient (by 7%) than CNC milling. The effect of post-processing on WAAM’s environmental and economic performance is also studied. WAAM is found to be more economical and ecological than CNC milling when the post-processing machining allowance of 4 mm or lower is left across the surface area of the propeller considered. This study can be helpful to AM practitioners in understanding the factors affecting WAAM’s sustainability and in decision-making on sustainable process selection.