Development of a combined machining method using electrorheological fluids for EDM

The objective of this study is to develop a new combined technology of electrical discharge machining (EDM) with polishing by using electrorheological (ER) fluid as working fluid. The surface of the work-piece after EDM has a recast layer with many micro-craters and cracks. Therefore, the polishing process is usually required after EDM for the molds applied on computer, communication and consumer electronics (3C) industries. In the study, we proposed a novel method of EDM that used ER fluid instead of water or oil and employed fine abrasive grits to carry out the combined process of EDM and polishing. The effect of this new electromechanical process combining EDM and polishing was investigated. The experimental results demonstrate EDM process still can perform in the ER fluid and polishing process can be surely performed after adding the alumina abrasives. We have a good performance to obtain surface roughness of Ra 0.08–0.06 μm when using alumina abrasives of 0.3 μm and discharge capacity of 0.01 μF in the proposed method.