Definition of Wire EDM

Electrical Discharge Machining (EDM), a manufacturing process whereby a desired shape is obtained using electrical discharges, is primarily used to cut hard metals and other materials that would be impossible to machine with traditional techniques. Sometimes referred to as "spark machining" or "spark eroding", EDM is a non-traditional method of removing material by a series of rapidly recurring electric arcing discharges in the presence of an energetic electric field. EDM can cut small or odd-shaped angles, intricate contours or cavities in pre-hardened steel.

The EDM cutting tool is guided along the desired path. Consecutive sparks produce a series of micro-craters on the workpiece and remove material along the cutting path by melting and vaporization. The particles are washed away by the continuously flushing dielectric fluid. It is also important to note that a similar micro-crater is formed on the surface of the electrode. These micro-craters result in the gradual erosion of the electrode, many times requiring several different electrodes of varying tolerances to be used or, in the case of wire EDM machining, constant replacement of the wire by feeding from a spool.

Wire-cutting EDM is commonly used when low residual stresses are desired. Wire EDM has no added residual stress because it has no cutting forces. There is little change in the mechanical properties of a material in wire-cutting EDM due to these low residual stresses.

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