Reducing Edge Chipping of Micro-holes with Electrophoresis-assisted Micro-ultrasonic Machining

Abstract This paper proposes the method of electrophoresis-assisted micro-ultrasonic machining (EPAMUSM) to reduce edge chipping when machining holes in hard and brittle materials. By utilizing the electrophoresis effect of ultra-micro abrasive particles in work solution and the effect of electrophoresis-assisted electrical field, the abrasive particles in the solution can be gathered around the micro-tool, thereby reducing the edge chipping caused by direct hammering between the tool and the workpiece. EPAMUSM helps to improve the utilization of the abrasive particles and significantly improves the material removal rate compared with micro-ultrasonic machining (MUSM). Both single-factor and orthogonal experiments were performed to verify the method. The results show that abrasive particles gathered around the tool with the assistance of the electrophoretic effect and electrical field, and that the utilization of abrasive particles was enhanced during MUSM, which weakened the direct hammering between the tool and the workpiece. With the best parameter values (a machining force of 0.1 N, an abrasive-particle diameter of 0.1 μm, an electrical field voltage of 5 V, and an ultrasonic power of 21 W), micro-holes of 100 μm in diameter could be generated well in monocrystalline silicon. Compared with conventional MUSM, there was less chipping around the hole edge and the quality and material removal rate were improved greatly.