EDM consists of the destruction of metal through a series of recurring electrical discharges between a cutting tool that acts as an electrode and a conductive part, which is the workpiece (seized bolt, for example). This destruction is carried out by a combination of fusion and thermal contraction of the material.

According to the Britannica Encyclopedia, the definition would be:

“EDM involves directing high-frequency electrical spark discharges from a graphite or soft metal tool, serving as an electrode, to disintegrate electrically conductive materials such as hardened steel or carbide.”

EDM is generally applied to destroy seized bolts and breakage of cores that remain blocked in their holes and cannot be extracted by traditional mechanical means (extractors, drilling, boring, etc.)
This method can be used from small 1mm metric holes to 20mm larger diameter holes, even though larger diameters can be studied with special procedures and tools.

With the adaptation of EDM equipment, it is possible to machine parts in situ that with other machining systems would be very complex.

EDM machining is independent of the hardness of the work material. Being an essentially thermal process, any material can be worked as long as it is conductive. It is usually used to machine alloys or very hard metals, elements difficult to machine due to chip removal.

Machining does not produce any deformation in the material, since the workpiece is not touched and the working frequencies are very high (the material does not get hot).

The EDM process may seem like a slow method of removing material, however it is a very fast technique for removing material.