Electric Discharge Machining

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ELECTRIC DISCHARGE MACHINING

INTRODUCTION
* Sometimes it is referred to as spark machining,
* Its a manufacturing process whereby a desired shape is obtained using electrical discharges (sparks). * Material is removed from the workpiece by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage. * One of the electrodes – ‘tool-electrode’ or ‘tool’ or ‘electrode’. * Other electrode - workpiece-electrode or ‘workpiece’. * As distance between the two electrodes is reduced, the current intensity becomes greater than the strength of the dielectric (at least in some points) causing it to break. * EDM is a machining method primarily used for hard metals or those that would be very difficult to machine with traditional techniques. * EDM typically works with materials that are electrically conductive, although methods for machining insulating ceramics with EDM have been proposed. * EDM can cut intricate contours or cavities in hardened steel without the need for heat treatment to soften and re-harden them. * This method can be used with any other metal or metal alloy such as titanium, hastelloy, kovar, and inconel. EDM – Working Principle

* It is a process of metal removal based on the principle of material removal by an interrupted electric spark discharge between the electrode tool and the work piece. * In EDM, a potential difference is applied between the tool and workpiece. * Essential - Both tool and work material are to be conductors. * The tool and work material are immersed in a dielectric medium. * Generally kerosene or deionised water is used as the dielectric medium. * A gap is maintained between the tool and the workpiece. * Depending upon the applied potential difference (50 to 450 V) and the gap between the tool and workpiece, an electric field would be established. * Generally the tool is connected to the...
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