Manufacturing and milling behaviours of recycled and virgin reinforced technical polymeric parts fabricated by BAAM

Thermoplastic recycling via screw extrusion is a central enabler of circular and sustainable additive manufacturing, with widespread application in aerospace, automotive, and energy industries. Despite its relevance, limited understanding persists regarding the machining behavior of these materials during final precision-cutting operations. This study proposes a simple and economically viable industrial recycling strategy for engineering plastics, aimed at extending their life cycle. Recycled PEI exhibits a 16% reduction in mechanical properties along the bead direction and a 90% increase in porosity compared to virgin material. Nevertheless, milling performance shows satisfactory surface quality, 23% lower torque, and improved machinability with discontinuous chips and reduced adhesion wear under dry conditions. Overall, the hybrid process enables the effective revalorization of recycled polymers for secondary industrial applications with lower performance requirements.