A gap-active electrical discharge machining (GA-EDM) to rectify the textural defects of the processed surface

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Gap-active electrical discharge machining (GA-EDM) is a novel approach which provides a gap-sensible and auto-adjustable electrode-retraction system. This mechanism is conceptualized from the principle of ‘parallel-plate capacitor having two dielectric mediums’ where the inter-electrode surfaces are acted as the parallel plates. The kerosene is used as a fundamental dielectric substance, and a relatively denser and viscous layer of bio-oil is treated as secondary dielectric material. Besides this, a servo-controlled tool arrangement is employed, which is auto-sensible and synchronized with the flushing system. This multi-dielectric enhances the equivalent capacitance of the plasma-column and can dissipate huge energy during the discharging phase. The extensive heat melts most of the solidification defects and reforms the entire texture, which is far better than the surface developed with normal EDM. Moreover, the viscous layer of the secondary fluid (above the workpiece) provides an adhesive grip and slow heat dissipation procedure, which can check the formation of micro-cracks, develop due to residual effect of rapid quenching. Besides these, the flushing sensible electrode retraction system ensures an adequate passage for flushing, which helps in proper debris-expelling and controlled heat dissipations. Therefore, the adopted gap-active (GA) mechanism can facilitate better textual features with negligible indentation, solidified-agglomerates, and cracks. It is observed that the secondary dielectric enriches the carbon containments in the texture and forms a 10–14 % harder surface than the normal-EDM.