Study on manufacturing quality of micro-ultrasonic machining with force control

Micro-ultrasonic machining (MUSM) is an effective way of processing microstructures made from hard and brittle materials, although controlling the fluctuation of the machining force during processing is difficult. To control the quality of micro-holes fabricated in hard and brittle materials, MUSM with force control (MUSMFC) is used to study the edge chipping rate (ECR) and material removal rate (MRR) during micro-hole fabrication. The process is controlled using a force sensor and a processing control strategy. Various experiments are designed to assess the processing efficacy. Comparative experiments indicate that the ECR with MUSMFC is superior to that with traditional MUSM. Single-factor experiments show that the ultrasonic power and the fluctuation of the machining force exert a significant influence on the ECR. The influence of the spindle speed on the ECR is small. Orthogonal experiments show that the fluctuations of the machining force and ultrasonic power have large impacts on the MRR. The spindle speed has a significant impact on the MRR as well, whereas the mass fraction has little effect. The best combination of ECR and MRR is obtained using a spindle speed of 500 rpm, a machining-force fluctuation of 0.1 N, an ultrasonic power of 50 W, and a mass fraction of 10%.