One Step Fabrication of Micro-hole on SiCp/Al Cambered Surface by Micro-EDM and Mechanical-reaming Combined Machining

SiCp/Al, as a new material, is widely used for its excellent wear resistance, corrosion resistance and other properties. Micro-holes are important but difficult to obtain on this ceramic material especially in curved surface. In this paper, taking micro bearing bush as an example, a micro-EDM and in-situ micro-reaming method is put forward for preparing micro through holes and micro eccentric holes on SiCp/Al cambered surface, without secondary clamping or tool change. High machining efficiency, low wear and no recasting layer can be achieved by this method. Here, machining characteristics is studied in hole micro-EDM on SiCp/Al, small taper and high efficiency machining is realized by comparing four electrical discharge drilling technique. Carbon deposition and tool wear are related to electrical parameters according to experimental exploration. After determining the discharge gap, taper and recast layer thickness, a segmented tool is designed, which can use the lower part to perform micro-EDM with the taper of 1.04°, MRR is 0.069 mm³/min, and the TWR is 3.22%. Then only needs to continue feeding the tool, the upper part of the tool can be used to achieve reaming, which can fully remove the recast layer, and decreases the roughness of hole wall from Ra 1.452 μm to Ra 0.803 μm.