Electric discharge machining (EDM) or Electrode Discharge Machining is a machining process that uses electrical discharges (sparks) to remove unwatned portion from a workpiece. In the process, a series of rapidly recurring current are discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage. EDM is a machining method primarily used for hard metals or those that would be very difficult to machine with traditional techniques.
The advantages of EDM include
- Machining of complex shapes
- Machining of extremely hard material to very close tolerances
- Machining of very small work pieces
- Almost no direct contact between tool and work piece.
- Good surface finish
The disadvantages of EDM include:
- Slow material removal rate
- Additional time and cost in setup
- Not good for sharp corners on the workpiece due to electrode wear
- High power consumption
- Limited to electrically conductive materials, although non-conductive materials are possible in certain setup