Electrical discharge machining in gas

In this paper, we show that electrical discharge machining (EDM) can be achieved in gas. With the help of a high-pressure gas flow supplied through a thin-walled pipe electrode, the molten workpiece material can be removed and flushed out of the working gap without being reattached to the electrode surfaces. The greatest advantage of this technique is that the tool electrode wear ratio is almost zero for any pulse duration. Hence a 3D shape can be machined very precisely using a special NC tool path which can supply a uniform high-velocity air flow over the working gap. Furthermore, the material removal rate is improved as the concentration of oxygen in air is increased, due to oxidation of the electrode materials.