Novel insights into conventional machining of metal additive manufactured components: a comprehensive review

Metal-based additive manufacturing (AM) displayed a revolutionary influence in the world of engineering and opened the doors to new opportunities for individuals as well as for industries. The design flexibility and high mechanical performance make this process more widespread and popular. Furthermore, the usage of minimal material with less wastage and the lowering of tooling expenses stands out as noteworthy benefits of the AM process. Nonetheless, an inherent limitation of AM printed materials includes issues related to the unique microstructure of AM parts, such as varying material densities, anisotropic properties and residual stresses. These factors can lead to unpredictable tool wear, poor surface finish and dimensional inaccuracies during machining operations. Additionally, the presence of hard inclusions or defects within the printed material can further exacerbate tool wear and increase machining difficulty. As a result, machining processes are often required to obtain the desired surface quality of the component. This study undertook a comprehensive and systematic review of the machinability of metal additive manufactured (AMed) components, contrasting them with wrought materials based on their response parameters. It investigated the turning, milling and drilling performances of AMed components, examining factors such as cutting forces, tool morphology, chip formation, hole quality, surface integrity, tool wear and temperature. This analysis encompassed diverse cutting conditions, building orientations and machining environments including flood, MQL, cryogenic cooling as well as AM parameters and post-heat treatments. Furthermore, this study places a significant emphasis on the sustainable attributes of the cutting fluids utilized in the machining of AM parts, alongside the overall sustainability of the manufactured components. It aims to pinpoint pivotal research findings and constraints while proposing avenues for future research endeavors. The main goal of this review is to furnish a comprehensive resource that consolidates knowledge regarding the surface quality and machinability of AMed metallic objects. Furthermore, it offers suggestions on machining strategies and insights into challenges and potentials related to machining AM parts. Additionally, it provides recommendations to enhance their machinability. Finally, the article introduces potential directions for future research to advance the field and enhance the efficacy of the AMed part.