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Electrical discharge machining

Electrical discharge machining (EDM), also known as spark erosion or spark eroding, exists in two main forms, die sinking and wire cutting. It is a machining process that uses electrical discharge (sparks) to remove material from a workpiece and achieve the desired shape. Current is discharged between two electrodes in a dielectric liquid to which voltage is applied.

One of these electrodes is the tool electrode, the other the workpiece electrode. Discharge is made possible by the distance between the two electrodes, tool and workpiece. From a certain voltage, the electric field in the dielectric between the electrodes causes current to flow between them, a process on the same principle as the breakdown of a capacitor (condenser). The discharge causes material to be removed from both tool and workpiece. Since the voltage is discontinuous, dielectric can flow into the space between the electrodes to flush away the solid debris and restore the dielectric’s insulating properties. This also restores the potential difference between the electrodes so that the discharge cycle can be resumed.

When purchasing an EDM, low operating cost (wire consumption, electricity) and low maintenance are important factors. The price-performance ratio is critical. A beneficial feature of advanced machines is auto threading in the event of wire breakage. Ultimately, it is solidly built machines that stand the test of time as they offer the most reliability in the long run.