Process selection charts based on economy and environment: subtractive or additive manufacturing to produce structural components of aircraft

Multi-criteria decision-making methods are commonly used to rank manufacturing processes based on weighted economic and environmental criteria. The weighting process can be challenging, especially at early design stages where costs and environmental data are not precisely defined. In addition, for weights resulting in equivalent alternatives, no conclusion can be drawn when costs and environmental impact data are scarce and heterogeneous. Therefore, new methodology and tools are needed to find trade-offs between economy and environment in selecting manufacturing processes. In this work, a new systematic methodology for manufacturing process selection using fuzzy logic is developed. Applied to neutral, environmentalist and economist modes of thinking, manufacturing process selection charts were generated for all cost and environmental impact values. These tools were used to compare machining and selective laser melting for the production of aluminum structural components of aircraft. Results show that selective laser melting is the best trade-off in the mindset of neutrals and environmentalists, while machining is preferred by economists. Moreover, the proposed methodology can be used in situations where costs and environmental impacts are defined as ranges rather than determined numerical values. This methodology ranks manufacturing processes when weighted-criteria methodologies are limited.