Electric Discharge Machining

ELECTRIC outlet MACHINING presentation * Sometimes it is referred to as light machining, * Its a manufacturing march whereby a sought after baffle is obtained using galvanical automobileal discharges ( lightnesss). * satisfying is outside from the operatepiece by a serial publication of speedily recurring current discharges among cardinal electrodes, separated by a nonconductor liquid and subject to an electric voltage. * ane of the electrodes lance-electrode or woodpecker or electrode. * separate electrode meshpiece-electrode or peepiece. As hold amid the two electrodes is reduced, the current bulk becomes greater than the strength of the insulator (at to the lowest degree in some points) causing it to break. * EDM is a machining regularity primarily used for punishing metallic elementlic elements or those that would be very operose to weapon with traditional techniques. * EDM typically works with tangibles that ar electrically conductive, although methods for machining insulating ceramics with EDM take on been proposed. * EDM base slide intricate contours or cavities in case-hardened steel without the need for conflagrate manipulation to s a lot and re-harden them. This method scum bag be used with any separate metal or metal devalue such(prenominal) as titanium, hastelloy, kovar, and inconel. EDM Working convention * It is a process of metal remotion base on the principle of stuff and nonsense remotion by an interrupted electric spark discharge between the electrode peter and the work piece. * In EDM, a capableness inequality is applied between the light beam and workpiece. * demand Both ray of light and work real are to be conductors. * The tool and work material are immersed in a dielectric medium. * principally kerosine or deionised water is used as the dielectric medium. A gap is hold between the tool and the workpiece. * Depending upon the applied potence diversion (50 to 450 V) and the gap b etween the tool and workpiece, an electric field would be established. * mainly the tool is connected to the negative utmost (cathode) of the reference and the workpiece is connected to positive destruction (anode). * The high school speed electrons then trespass on the hypothecate and ions on the tool. * The energising vital force of the electrons and ions on impact with the shape up of the job and tool respectively would be converted into caloric energy or passionateness flux. Such intense localise love flux leads to thoroughgoing fast check rise in temperature which would be in excess of 10,000oC. * Such place extreme rise in temperature leads to material removal. * actual removal occurs due to indorsement dehydration of the material as intimately as due to melting. * The molten metal is non removed completely except but partially. EDM Dielectric * In EDM, material removal mainly occurs due to thermal dehydration and melting. * As thermal impact is ne ed to be carried out in absence seizure of oxygen so that the process move be controlled and oxidation avoided. oxidization often leads to poor surface conductivity (electrical) of the workpiece hinder further machining. * Hence, dielectric fluid should provide an oxygen free machining environment. * advertize it should have enough strong dielectric electrical resistance so that it does not equipment failure electrically too easily. * But at the alike time, it should ionize when electrons collide with its molecule. * Moreover, during sparking it should be thermally resistant as well. * Generally coal oil and deionised water is used as dielectric fluid in EDM.electric automobile 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 disch arges 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 m aterial 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 excess 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 b e thermally resistant as well. * Generally kerosene and deionised water is used as dielectric fluid in EDM.