Below is a list of Ram EDM manufacturers from Chicago, Illinois. Ram EDM, or electrical discharge machining, goes by many names including conventional EDM, sinker EDM and cavity type EDM. It produces parts through eroding material in the path of an electrical field using electrical discharges, or sparks that can generate heat anywhere from eight to twenty thousand degrees. Ram EDM is used for more complex geometries where electrodes are used to erode the desired shape into the part or assembly.