Optimization Using Evolutionary Algorithms and Metaheuristics by Kumar Kaushik; Davim J. Paulo;

Author:Kumar, Kaushik; Davim, J. Paulo;
Language: eng
Format: epub
Publisher: Taylor & Francis Group
Published: 2019-08-19T00:00:00+00:00

4.1.2 Mechanism of EDM Process

During the electrical discharge machining process, the material is removed from the workpiece owing to erosion by repeated electric spark discharge occurring in the electrode and workpiece. A tiny gap is maintained between the tool and workpiece by a servo system, and both electrode and workpiece are submerged in a dielectric fluid (Pradhan et al. 2009a). The electrode generally acts as a cathode, and the workpiece acts as an anode, and a high and potential difference is applied. When the voltage is sufficiently developed through the interval, it discharges through the gap as a spark in the very small interval (one-tenth of a microsecond), the electrons and positive ions are accelerated, generating a discharge channel that becomes conductive. It is a point where the spark jumps and causes a collision between electrons and ions, creating a plasma channel. The plasma channel is no longer sustained. It produces pressure or shock waves, which preceding the molten material creates a crater of the material at the location of the spark. An instant drop in the electric resistance of the preceding spark allows current density to reach extremely high values, creating enhanced ionization and the formation of a powerful magnetic field (Pradhan and Das 2011). The instant spark takes place, and sufficiently high pressure is developed between electrode and workpiece. Such localized extreme rise in temperature leads to melting and immediate vaporization of the material, which are eroded by the flushing of the dielectric (Pradhan et al. 2009b and 2009c; Das and Pradhan 2013).

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