Manufatura aditiva de PLA extrudado associada à manufatura subtrativa objetivando tolerâncias dimensionais e geométricas mais estreitas: uma abordagem híbrida

Abstract

Advanced manufacturing employing additive and subtractive processes has been gaining prominence in the manufacturing of optimized functional components. Even though it is an embryonic area, the association of manufacturing in the context of hybrid processes, especially in the aerospace and medical industries using metallic alloys, has fostered important technological advances by reconciling multi-scale geometric complexity, new materials and mechanical and physicochemical performance. However, research, technologies, regulatory standards, and industrial applications of hybrid processes focused on polymeric and composite materials are still incipient. In this context, this research aims at additive manufacturing by Fused Filament Fabrication (FFF) associated with subtractive manufacturing aiming tighter dimensional and geometric tolerances as a hybrid approach. FFF parameters of the PLA thermoplastic were chosen with a focus on mechanical performance. For external cylindrical turning, cutting tool geometry, speed (vc), feed (f) and depth of cut (ap) were varied. Dimension, roughness, profilometry, roundness, cylindricity, cutting force (Fc), scanning electron microscopy (SEM) and optical microscopy were analyzed. The results show significant improvement in dimensional and geometric tolerances. The dimensional uncertainty values were reduced from 0.06 mm to 0.02 mm. The average reduction of the roughness parameter Ra was 89.6% for the DCGX 070204 AL tool, which presented the best results. The average roundness and cylindricity deviations were reduced by 91 % and 81 %, respectively. The shape and roughness deviations were affected by the material adhesion on the workpiece. The most influential parameters on the roughness were f and ap. Fc increased with reducing the rake angle of the cutting tool, and was most influenced by f and ap. In the hybrid context, the associated processes achieved unique results that could not be found in isolation, pointing paths to the development of machines, manufacturing processes and software integrated within the advanced manufacturing cell in full synergy with the part design.