What can EDM do?

EDM or electric discharge machining uses electricity to vaporize metal in a very precise manner. If you have ever dropped a wrench across a car batteries tewrminals you probably witnessed a crude form of EDM. Wire EDM uses a spool of wire, usually brass, to conduct the electricity. Wire EDM is used when cutting all the way through a part. The upper head can move independently of the lower head to cut tapers or even different shapes on the top and bottom of the part. The advantage of wire EDM is that the electrode is a spool of wire and does not need to be manufactured. Sinker or conventional EDM is used when the cut is not all thew way through such as a hex in the head of a bolt. Electrodes are usually made of graphite or copper, and in some cases copper tungsten or silver tungsten. The EDM process works with high frequencies, turning the spark on for a few microseconds, then turning it off for a few more depending on the application. The spark vaporizes the metal, then during the off time the dielectric fluid cools the vapor into tiny particles. It happens so quickly the part and electrode do not get hot.
EDM is used to cut when conventional machining such as milling or turning is not practical or possible. We often receive parts that are 90% completed on conventional machines, that need an area machined that couldn't be reached with a cutting tool, such as a sideways hole inside a bore or sharp inside corners.
These are a few of  the many applications where EDM is used: Stamping dies, molds, prototype parts, aerospace parts, medical parts, cutting carbide tools, cutting involute splines and gears, removing broken taps and drills, splitting rings and hubs, drilling small holes, cutting hexes in fasteners, form tools, shims, extrusion dies, and miniature parts.
EDM is very accurate, we often hold tolerances of .0001" or .0025mm.