3. Electrochemical Machining

Electrochemical machining has attracted increasing attention for micro-machining applications. The first section discusses a process to erode a hole of hundreds of microns diameter in a metal surface using a moving electrode. The discussion provides a method to predict the enlargement of the produced hole and to taper under the applied machining conditions. A computational model illustrates how the machined profile develops over time and as the electrode gap changes. The analysis is based on Faraday’s laws of electrolysis and the mathematical integral describing a tool. The effectiveness of the model is tested by experiments that apply several electrode movement schemes.

This chapter discusses the surface roughness of several common die materials produced by traditional machining, whereby the internal and external cylindrical surface are electropolished by different electrode designs. Electropolishing efficiency of die materials and parts should be high to improve surface roughness in the shortest amount of time possible, thereby reducing surface residual stresses. The study aims to identify an optimal electrode design, which will help broaden electromachining applications in the future. For electropolishing of internal holes, completely inserted feeding electrodes are supplied with both continuous and pulsed direct current. In the external electropolishing studies, we consider the design of the turning tool electrode, arrowhead electrode, ring-form electrode, and disc-form electrode. For internal electropolishing, an electrode featuring a helix discharge flute performs better than that without a flute or with a straight flute. The borer type electrode performs better an electrode with a lip on the leading edge. Pulsed direct current can improve the polishing, but the machining time and costs are increased. In the case of external electropolishing, a smaller nose radius or end radius produces greater current density and provides a faster feed rate and better polishing. Ultrasonic-aided electropolishing improves the polishing effect with no increase in machining time, thus improving efficiency and reducing costs.