Machinability of Sintered Metallic Materials in Additive Manufacturing

Additive manufacturing (AM) technologies based on sintering, such as Powder Bed Fusion (PBF), Direct Energy Deposition (DED), Binder Jetting (BJT), and Material Extrusion (MEX), enable the production of complex metallic components with reduced material waste and design flexibility. However, the intrinsic porosity, microstructural anisotropy, and mechanical properties of sintered AM metals significantly influence their machinability, affecting tool wear, surface integrity, and cutting forces. This review explores the key material characteristics affecting the machining performance of sintered AM metals, focusing on conventional processes such as turning, milling, and drilling. The impact of microstructure, density, and mechanical properties on machining outcomes is analyzed, along with the challenges posed by the unique properties of sintered materials. Additionally, post-processing strategies, including heat treatments and surface finishing techniques, are discussed as potential solutions to enhance machinability. The review concludes by identifying future research opportunities, particularly in optimizing AM process parameters and developing hybrid manufacturing approaches to improve the industrial applicability of sintered AM metallic materials. Although previous studies focus on individual AM technologies, this review takes a novel approach by systematically comparing the machinability of metallic materials produced via PBF, DED, BJT, and MEX. By identifying commonalities and differences among these sintering-based AM processes, this work provides a comprehensive perspective on their machining behavior and post-processing requirements, offering valuable insights for industrial applications.