In EDM, or electrical discharge machining, the equivalent of tiny lightning bolts perform the material removal. Though slow in terms of metal removal rate, EDM is capable of machining complex shapes in hard materials. Mold and die makers, as well as makers of jet engine components, rely on EDM routinely. The process includes an electrode and a workpiece, both submerged in dielectric fluid. Current flows between the workpiece and electrode, repeatedly creating tiny plasma zones with temperatures around 10,000 degrees C. The high temperatures produce localized, instantaneous melting of the material. Though the process may seem violent, it occurs on such a tiny scale that the resulting metal removal can be precisely controlled. The electrode in EDM takes different forms. Wire EDM machines use a thin wire to cut with electricity, with the wire advancing into the hard metal part as if it was a slow-motion saw blade. By contrast, ram EDM machines, which are also called “die sinkers,” use electrodes that are custom machined into 3D shapes. The EDM process then produces a cavity in the part that is the opposite or female version of the “male” electrode form. Similar to the ram EDM machine is the small-hole EDM machine, or “hole popper.” On this machine, the electrode is a cylinder used to machine a hole. Often these machines are used simply to provide starter holes for wire EDM, but the technology may also be used to machine finished holes in materials that are too difficult to drill.