Advanced Manufacturing Routes for VTOL UAV Component: A Life Cycle Comparison of CNC Milling, Selective Laser Melting, and Metal Extrusion

Additive manufacturing (AM) has emerged as an enabling technology for producing lightweight and geometrically complex components in aerospace applications. This study investigates alternative manufacturing routes for a critical servo bracket used in a Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicle (UAV) platform, aiming to comparatively evaluate their environmental, economic, and operational performance within a life cycle perspective. The servo bracket was manufactured using CNC milling, Selective Laser Melting (SLM), and Metal Extrusion Additive Manufacturing (MEX/M) and the three routes were assessed using Life Cycle Assessment (LCA), Life Cycle Cost (LCC), and process-based indicators, including production time and production process. The results indicate that CNC milling exhibits the highest carbon footprint per part (156.3 kg CO2-eq.), mainly due to aluminium chip waste, whereas electricity consumption is the dominant contributor in SLM. Production times were 8.9 h for CNC, 52.7 h for SLM, and 71.6 h for MEX/M. From an economic perspective, CNC provides the lowest unit cost, while SLM is associated with the highest cost due to machine depreciation. Overall, the findings highlight distinct trade-offs between conventional and metal additive manufacturing routes and provide a life cycle-based decision framework for selecting suitable manufacturing strategies for VTOL UAV structural components.