Electric Discharge machining (EDM) is also known as spark erosion. This process works by inducing a spark between the electrode and the work-piece that results in a very small crater on the surface. By repetitive sparking (pulsation) more material is removed, the waste material is then washed away. Like ECM the material closest to the electrode is affected first, simply because the current chooses the path of the least resistance.

Sinker EDM

This type of EDM is the best known due to its use in mold production (die sinking). It can be used for creating all kinds of shapes that otherwise are almost impossible to produce. Another application using the sinker EDM principle is the drilling of holes too small or on impractical surfaces for mechanical drilling.

Wire EDM

Although the principle of material removal is the same, the application and the required electrode are very different. Instead of a negative image, the electrode is a piece of wire that (like a band saw) runs through the material to cut out the desired shape. Mainly used for cutting materials either too hard or too thick to process using traditional tools.