How does a plunge EDM work?
Plunge EDM machines, also know as ram EDM or spark drills, burn the material from one side, using an electrode that pushes the material out of the way as it works its way into the block of material. Unlike a wire EDM, plunge EDMs can start on one side of the material and burn their way through it. They are therefore ideal for blind holes. The shape of the hole burnt by the EDM is determined by the shape of the electrode burning the hole. The electrode is fixed, and as with a wire EDM, continuously flushed with dialectric fluid. If one uses an electrode with a square cross section, one will make a square hole. The working end of the electrode can also have 3D shape, allowing tapers, concave or convex surfaces to be burnt into the material.
