| Electrical Discharge Machining (EDM) is ideal for intricate burr-free cutting of intricate contours or cavities in hard materials, eliminating the need to soften the material before machining, and then re-harden it through heat-treating. The process can be used with stainless steel or other electrically conductive materials including titanium, Hastelloy®, Inconel®, nitinol and Kovar®.
Also called "spark machining," "spark eroding," "burning," "die sinking," and "wire erosion," the process uses electrical discharges between an electrode (the cutting tool) and the work piece, both immersed in a dielectric liquid (typically de-ionized water or dielectric oil), to remove material from the part.
EDM offers consistent results and is particularly suited for parts requiring tight tolerances. Extra fine surface finishes can be obtained and near perfect perpendicularity achieved using EDM.
MicroGroup has proprietary fixtures, which permit the cutting of extremely small diameters (down to Ø0.001") and to very short lengths (<0.005"). EDM cutting can produce edges with minimal edge break which may be desired for welding or other joining applications.
MicroGroup offers both main types of EDM as follows:
Wire EDM
Wire EDM uses a single-strand wire (typically brass) that is fed through the work piece to perform the cutting. The gap between the electrode and the work piece is
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typically flushed with de-ionized water. This is a highly repeatable and consistent process that is excellent for exact lengths and other tight tolerances.
Sinker EDM (also known as RAM EDM, Cavity EDM, Volume EDM or Conventional EDM)
Instead of using a wire as the electrode, Sinker EDM uses a graphite electrode, which is the negative shape of the feature being produced, to remove material as it "sinks" into the part. Also unlike Wire EDM, Sinker EDM need not cut completely through the part. These characteristics make Sinker EDM ideally suited to machining of burr-free holes, slots, or complex shapes in bar, tube or flat stock.
Sinker EDM uses a dielectric oil to control the rate of burning and to flush debris away to prevent arcing out. Since the electrode will wear as parts are burned it will require re-machining over time.
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