Critical Review on the Sustainability of Metal Additive Manufacturing: Environmental and Economic Perspectives

Manufacturing is an important pillar of socio-economic development, but it has a large carbon footprint and causes serious damage to the ecosystem. There is significant pressure on the manufacturing sector to embrace eco-friendly manufacturing technologies to reduce its environmental burden. Metal Additive Manufacturing (MAM) is a rapidly evolving field with promising prospects to balance the economic and ecological concerns. Recently, manufacturing businesses started to examine MAM as a potential route to strengthen their eco-footprint and improve sustainability performance. The shift from Conventional Manufacturing (CM) processes to MAM requires significant capital investment, staff training, and possibly changing the business model. This may lead to hesitancy among enterprises to take on such risks without guaranteeing the sustainability benefits of MAM. This paper conducts a comprehensive review and critical evaluation of the environmental and economic impacts of MAM. The paper draws guidelines on the best production contexts that enable the fulfilment of environmental goals and maintain economic viability through MAM technologies. In general, Powder Bed Fusion (PBF) techniques are considered environmentally friendly and cost-effective for small-scale production of lightweight small parts with complex shapes and relatively high resolution. In contrast, Direct Energy Deposition (DED) processes are valuable for repairing and manufacturing large-scale parts that have medium shape complexity and relatively low resolution.