Sustainability comparison of wire arc additive manufacturing (WAAM) and pure machining using LCA, environmental prices and cost analysis: a case study on a low carbon steel pipe reducer

Manufacturing complex steel components by pure machining generates substantial material waste and requires considerable energy, motivating a shift toward near net shape technologies. Although Wire Arc Additive Manufacturing (WAAM) is a promising alternative, the literature lacks integrated, high fidelity assessments that address the economic and environmental uncertainties associated with industrial adoption. This study compares WAAM with pure machining for a low carbon steel eccentric pipe reducer measuring 77 mm in lower diameter, 73 mm in height, and 40 mm in upper diameter. The assessment integrates a cradle to gate Life Cycle Assessment (LCA) based on ReCiPe 2016 Midpoint (H) and Endpoint (H), Environmental Prices to monetize external societal costs in a single monetary score, Life Cycle Costing (LCC) to evaluate economic feasibility, and Monte Carlo simulation to assess uncertainty. WAAM reduced material waste by 61%, water consumption by 60%, and global warming potential by 45%. It also reduced impacts in eight other categories, including land use by 89% and marine eutrophication by 92%. However, WAAM increased fine particulate matter formation by 33% and terrestrial ecotoxicity by 88%, indicating a need for targeted fume management. Environmental Prices showed that WAAM reduced external societal costs by 10%, from 1.72 to 1.55 USD per unit. At the reference condition of 500 FU per year and ten substrate reuse cycles, WAAM achieved an approximately 6% deterministic operating cost advantage. The Monte Carlo simulation for 500 FU also indicated a narrower 90% confidence interval for WAAM, from 1551 to 1862 USD, than for machining, from 1490 to 2061 USD. These findings indicate that WAAM is a technically feasible option with substantial environmental benefits and potential operating cost advantages for the investigated component.