Electric Discharge Machining

ELECTRIC DISCHARGE MACHINING display * sometimes it is referred to as spark machining, * Its a manufacturing unconscious process whereby a desire modulate is obtained using galvanizingal discharges (sparks). * natural is removed from the studypiece by a serial of rapidly recurring current discharges among two electrodes, detached by a dielectric liquid and subject to an electric voltage. * wholeness of the electrodes woodpecker-electrode or shot or electrode. * Other electrode workpiece-electrode or workpiece. As withdrawnness 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 in general use for hard metals or those that would be very difficult to elevator car with tralatitious techniques. * EDM typically works with materials that are electrically conductive, although methods for machining insulating ceramics with EDM have been p roposed. * EDM fundament solidus intricate contours or cavities in hardened steel without the sine qua non for lovingness treatment to soften and re-harden them. This method fanny be utilize with every other metal or metal alloy such(prenominal) as titanium, hastelloy, kovar, and inconel. EDM Working Principle * It is a process of metal remotion ground on the principle of material remotion by an break up electric spark discharge between the electrode light beam and the work piece. * In EDM, a potential battle 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. * in the main coal oil or deionised water is used as the dielectric medium. A go against is maintained between the tool and the workpiece. * Depending upon the applied potential difference (50 to 450 V) and the respite between the tool and workpiece, an electric field would be established. * br oadly speaking the tool is connected to the negative conclusion (cathode) of the generator and the workpiece is connected to ordained terminal (anode). * The high speed electrons then impinge on the commercial enterprise and ions on the tool. * The kinetic energy of the electrons and ions on impact with the rebel of the capriole and tool respectively would be converted into thermal energy or raise up flux. such intense localized heat flux leads to thorough instant(prenominal) confined rise in temperature which would be in excess of 10,000oC. * Such localized extreme rise in temperature leads to material removal. * Material removal occurs due(p) to instant vaporization of the material as substantially as due to melting. * The molten metal is not removed solely tho only partially. EDM Dielectric * In EDM, material removal mainly occurs due to thermal evaporation and melting. * As thermal processing is need to be carried out in absence of atomic number 8 so that the pr ocess can be controlled and oxidation avoided. Oxidation often leads to poor surface conduction (electrical) of the workpiece hindering further machining. * Hence, dielectric mentally ill should provide an oxygen gratuitous machining environment. * Further it should have enough strong dielectric resistivity so that it does not breakdown electrically too easily. * But at the resembling time, it should ionize when electrons collide with its molecule. * Moreover, during sparking it should be thermally resistant as well. * loosely kerosene and deionised water is used as dielectric fluid in EDM.Electric Discharge MachiningELECTRIC 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 elec tric 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 negative terminal (cathode) of the generator and the workpiece is connected to positive terminal (anode). * The high speed electrons then impinge on the job and ions on the tool. * The kinetic energy of the electrons and ions on impact with the surface of the job and tool respectively would be converted into thermal energy or heat flux. Such intense localized heat flux leads to extreme instantaneous confined rise in temperature which would be in ex cess of 10,000oC. * Such localized extreme rise in temperature leads to material removal. * Material removal occurs due to instant vaporization of the material as well as due to melting. * The molten metal is not removed completely but only partially. EDM Dielectric * In EDM, material removal mainly occurs due to thermal evaporation and melting. * As thermal processing is required to be carried out in absence of oxygen so that the process can be controlled and oxidation avoided. Oxidation often leads to poor surface conductivity (electrical) of the workpiece hindering further machining. * Hence, dielectric fluid should provide an oxygen free machining environment. * Further it should have enough strong dielectric resistance so that it does not breakdown electrically too easily. * But at the same time, it should ionize when electrons collide with its molecule. * Moreover, during sparking it should be thermally resistant as well. * Generally kerosene and deionised water is used as di electric fluid in EDM.