EDM tooling, electrodes, fixtures, materials, guides and other supplies are used in electrical discharge machining (EDM), a highly-accurate manufacturing process for creating shapes within components and assemblies. EDM connects a metal workpiece to a power supply and uses a shaped tool or electrode to erode material in order to form the desired geometry or pattern. The electrical discharge is of very short duration and high current density. There are two basic types of EDM machines: wire and probe. Wire machines pre-drill a hole in the workpiece and then feed an electrode through the hole. Sinker machines cut workpieces without pre-drilling holes and typically use a machined graphite or copper electrode. To create a potential difference between the part and the electrode, the workpiece is often immersed in a circulating dielectric fluid.