Grinding process, surface characteristics, and machining performance of α/β-SiAlON ceramic double-circular-arc end mill

SiAlON ceramics are widely used for high-speed and high-efficiency machining of superalloys due to their excellent heat resistance. However, their inherent brittleness complicates the grinding process, often leading to edge chipping and impacting machining performance. In this study, a novel spark plasma sintered α/β-SiAlON ceramic double-circular-arc end mill was designed, and a specialized grinding process was developed to address its unique geometrical features. The grinding process was systematically divided into five key steps: helix flute, Y-direction flank, chip space, secondary flank, and primary flank. Analysis of the grinding principle and surface characterization showed good ground surface quality due to the refined process and gentle grinding parameters, but significant microdefects were still observed. Material flaking, grain pull-out, brittle fracture, and crack propagation are key mechanisms in the material removal process. Machining tests demonstrated a reliable cutting performance of the developed end mill when machining Inconel 718, although tool failure ultimately occurred due to flank notch wear and rake face chipping. This study enhances the understanding of the fabrication and performance of SiAlON ceramic end mills and offers valuable insights for future developments in the field.