Experimental study on ultrasonic vibration–assisted drilling micro-hole of SiCf/SiC ceramic matrix composites

SiCf/SiC CMC has a broad range of applications, especially under extreme conditions, due to its excellent properties including high strength and stiffness, high wear and temperature resistance. However, these properties also bring new challenges to manufacturing. Traditional machining methods and ordinary cutting tools failed to fabricate high-quality parts that meet the manufacturing requirement, especially for drilling micro-holes. This paper intends to compare six commonly used tools for micro-hole drilling of SiCf/SiC CMC assisted by ultrasonic vibration: carbide drill, PCD drill, electroplated diamond abrasive tool, grinding drill, coated grinding drill, and PDC tool. First, the material removal process is theoretically analyzed, and the difference in tool life and machining quality of different cutting tools is analyzed from the point of view of the material removal process. Then, the influence of different kinds of tools on cutting forces, machining accuracy, and tool wear was also investigated through experiments, and the correctness of theoretical analysis was verified by experiments. The results show that the machining accuracy of the PDC tool is best, followed by the electroplated diamond abrasive tool. The machining accuracy of the grinding drill and coated grinding drill is poor with a bit of difference; PDC and coated grinding drill have less tool wear, while the grinding drill has slightly more severe tool wear. However, the tool wear of the electroplated diamond abrasive tool is severe. In summary, PDC tools are ideal for preparing SiCf/SiC composites.