Week 15: Advance Machining (Electrical discharge machining (EDM), electromechanical machining & grinding,)

Electric Discharge Machining

It is also known as spark erosion machining or spark machining. Material of workpiece removed due to erosion caused by electric spark. Working principle is described below.

Working Principle of Electric Discharge Machining

Electric discharge machining process is carried out in presence of dielectric fluid which creates path for discharge. When potential difference is created across the two surfaces of die electric fluid, it gets ionized. An electric spark/discharge is generated across the two terminals. The potential difference is developed by a pulsating direct current power supply connected across the two terminals. One of the terminals is positive terminal given to workpiece and tool is made negative terminal. Two third of the total heat generated is generated at positive terminal so workpiece is generally given positive polarity. The discharge develops at the location where two terminals are very close. So tool helps in focusing the discharge or intensity of generated heat at the point of metal removal.

Applications of focused heat raise the temperature of workpiece locally at a point, this way two metals is melted and evaporated.

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