EDM  (Electric Discharge Machining) is a NonConventional machining technique. Unlike conventional CNC machining which uses cutting knifes / tools, an EDM CNC machine shapes a workpiece by continuously charging electrons (electrical discharge / sparks) through electrodes. These sparks produce very high temperature that will erode the workpiece. Electrical control system ensures a fully controlled sparks that continuously erode and shape the workpiece. Dielectric liquid is used as a medium which functions to flush solid particles (the chips) from the erosion process, cooling the electrode and the workpiece, and as electricity conductor.

This technique was first discovered in 1770 by Joseph Priestly, a British scientist. However, his invention was still far from perfect and very inaccurate. Russian scientists then made further research in 1943 and found out that erosive process from sparks can be controlled and used for more accurate machining purposes. Development of modern EDM machines began during mid 1970’s, and started to be available for  commercial use during mid 1980’s.

This EDM technique uses thin metal wire (usually made from brass). The wire electrode is connected to an electrical control system that produces controlled sparks that will erode the workpiece. Mechanical control system positions the wire electrode and the workpiece to make the desired cut. Wire EDM is usually used to make tools and die.