Electrical Methods of Material RemovalCompetenciesElectrical Methods of Material RemovalSlide 4Slide 5Slide 6Electrical Methods of Material RemovalChapter 5CompetenciesIdentify the general operating principles of EDMElectrical Methods of Material RemovalElectrical Discharge Machining (EDM) - The process of removing metal with an electric arc.•The workpiece and cathode (shape of tool/ impression) are submerged in a dielectric fluid •Voltage is applied (DC 300V)•Material is arced away and flushed out by the dielectric fluid•Electrodes are usually made of graphite The material removal rate is influenced by the melting temperature of the workpiece material and is faster for materials of lower melting temperature.Electrical Methods of Material RemovalEDM is best suited for materials whose parts are: •Made of very hard (conducting) materials and •To have a high precision (or low surface roughness)•At a low production rate•To have some strange shapes which would be difficult to machine by conventional techniquesElectrical Methods of Material RemovalRAM EDM= Plunge EDM = Die Sinking EDM - complex cavities are formed by penetration of shaped electrode into the part. •Used to make dies for forging or punching operations. Wire EDM- Uses a wire to erode the sides of the hole to form two external surfaces, which can have an elaborate shape. •wire electrode is of brass, copper, tungsten or molybdenumElectrical Methods of Material RemovalAdvantages over faster methods of material removal: •Unaffected by the hardness of the workpiece. •Holes with extremely complex shapes can be made. •There is no distortion of the metal, and no burrs left. •Produces surfaces to very fine dimensional and roughness tolerances•EDM operates unattended. Disadvantages: •EDM is slow, expensive, and cannot be used on nonconductive
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