What is Electrical Discharge Machining (EDM)?

EDM is a process of thermal erosion through electrical discharges between an electrode and the material to be destroyed.
EDM is also known as electrical discharge machining or EDM which is characterized as a non-traditional method of material extraction. There are no mechanical forces, only thermal ones.

How it works EDM??

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.”

Where can we apply EDM?

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.


Advantages of EDM machining


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.

Example of EDM

on site repair of rusty bolts
Bolt EDM Machining
On site EDM in petrochemical industry

EDM’s final result

piece reconstructed by EDM process