Electrical Discharge Machining (EDM), also known as spark erosion, is a metal machining process that uses electrical currents to shape a workpiece through a conductor. The process is carried out with the help of sparks generated between an electrode, which acts as the tool, and the workpiece. These sparks cause erosion by melting and vaporizing tiny particles of material, creating small craters on the surface of the part. During EDM, the distance between the electrode and the workpiece is maintained between 0.0125 mm to 0.05 mm, which is sufficient to create an electrical arc. In this process, temperatures can reach between 8000°C to 12000°C. A dielectric fluid is used for cooling and removing the eroded particles that block the arc gap. The performance of the dielectric fluid, which depends on circulation speed, can be enhanced using a circulation pump or similar methods. Typically, the tool electrode, often made of copper, is the cathode (-), while the steel workpiece is the anode (+). However, steel electrodes, aluminum electrodes, tungsten-copper electrodes used in steel machining, and graphite electrodes used for rough machining are exceptions to this generalization. These electrodes can be used as positively charged, reverse-polarity tools.

History and Applications of EDM

In 1943, Russian scientists discovered that regardless of their hardness, metals could be eroded by spark discharges. This process involves localized melting and vaporization. A small amount of material is removed in the form of chips, and no mechanical cutting force is applied. All electrically conductive metals can undergo this process.

After 1960, with the development of electronic control systems, EDM technology also began to evolve. Various types of systems such as PNC Erosion, CNC Erosion, ZNC Erosion, and EDM Erosion emerged during this period.

EDM is used in processing forms that cannot be fully machined using classical chip-removal methods (lathe, milling, vertical CNC machining). It is particularly useful for intricate, tiny channels or sharp features that are difficult to machine. EDM is predominantly preferred in mold making and tooling industries.