Surface finishing of micro-EDM holes using deionized water

In this paper, with the use of deionized water, a finishing process of micro hole surfaces processed by micro electrical discharge machining (micro-EDM) is investigated. A micro hole is machined by micro-EDM using deionized water as a dielectric fluid. The inner surface of the hole is finished successfully via electrochemical dissolution in deionized water. The effects of finishing conditions such as the resistivity of deionized water, the voltage, the tool rotation and the finishing time on the surface quality and accuracy of the shape were investigated. After a finishing process using deionized water with a resistivity of 2 MΩ cm, a voltage of 80 V, a tool rotation of 1200 rpm and a finishing time of 6 min, the surface roughness was reduced considerably from 0.225 νm R_a after micro-EDM to 0.066 νm R_a.