Wear behavior and machining quality of novel high-sharp brazed diamond abrasive core drills during drilling SiCf/SiC composite micro-holes

SiCf/SiC composites have promising applications in aerospace industries. SiCf/SiC composite micro-holes are important components, such as gas film holes on turbine blades. However, micro-hole machining in the SiCf/SiC composite is challenging because of its excellent mechanical and physical properties and poor machinability caused by micro-hole constraints. Therefore, a novel brazed diamond abrasive core drill was designed to achieve high self-sharpness by continuously losing blunt diamond grits and exposing sharp diamond grits. The wear and self-sharpness of the developed drill were investigated and compared with those of an electroplated diamond core drill during ultrasonic vibration-assisted drilling of SiCf/SiC composite micro-holes. The material removal behaviors of SiCf/SiC composites, including drilling forces, exit tearing, hole dimensions, hole wall quality, and the wear of core drills, were also studied. The developed core drill demonstrated reduced drilling force and a significantly prolonged lifetime. Further, it achieved superior drilling performance, drilling accuracy, and micro-hole quality.