By: Arthur Cooper
Submitted: 2010-08-20 19:50:14 | Word Count: 664
Electric discharge machining (also known as spark machining, spark eroding, burning, die sinking or wire erosion) is a manufacturing process that is common for extremely hard metals that would be difficult to machine using traditional machining methods. It uses a series of rapidly recurring current discharges between two electrodes, eroding material from the work piece. EDM is commonly used in the mold-making tool and die industries, and is a common manufacturing method for prototype and production parts. It is also popular for the creation of dies for production of jewelry and badges, and small-hole drilling. Small hole EDM is common for drilling rows of holes in the edges of turbine blades for jet engines.
Sinker EDM
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Also known as the cavity-type or ram-type EDM, Sinker machines take their name from the fact that the electrode and the work piece are completely immersed in a fluid (usually a dielectric oil). The electrode then is "sunk" into the part of the metal that is to be eroded. When current is applied, a spark jumps from the electrode to the work piece and vaporizes metal at the rate of several hundred thousand sparks per second. Machine parameters can control the rate of metal removal and the final quality of the surface finish.
Wire-Cut EDM
In the wire-cut EDM process, a thin metal wire is fed through the work piece (usually a brass wire). Water is used to wash away the debris from the cutting process -- since this type of work usually calls for very intricate parts and close tolerances, it is crucial that the water is filtered carefully. A tiny bit of metal in the water can bridge the gap between the part and the wire that emits the spark, interfering with the process.
Resellers of used EDM equipment will typically carry such lines as Agie, Brother, Elox, Makino, Fanuc, Sodick, Charmilles and more. Some dealers of pre-owned EDM machinery will also offer installation, training, application support, reconditioning, financing, appraisals, brokerage services and auctions for this extremely specialized equipment.
A sampling of used EDM equipment may invlude various machines such as:
� 1998 Mitsubishi FX10 (X, Y and Z travels 14" x 10" x 8")
� 1996 Mitsubishi FX-1 water-jet wire threader, (X, Y and Z travels 14" x 10" x 9")
� 1996 Charmilles Robofil 290 water-jet wire threader (X, Y and Z travels 16" x 10" x 8", max. workpiece size 34" x 20" x 8"
� 2006 Sodick AQ537L water-jet wire threader with chiller and 4-axis linear motion drives (X, Y and Z travels 15" x 23" x 14", maximum workpiece size 31" x 21" x 14")
� 2004 Fanuc 1iC-S submerged CNC water-jet wire threader with onboard APT programmer and 31 square inch per hour cutting speed (X, Y and Z travels 22" x 15" x 12", maximum workpiece size 44" x 32" x 12")
� 1998 Sodick Moldmaker 3, with 3R Macro 16 Station Rotary Tool Changer, Sodick MOS-FETS 40 amp generator and standard NC orbiter
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