Fabrication of micro-slits using W-ECDM process with textured wire surface: An experimental investigation on kerf overcut reduction and straightness improvement

Abstract

In this work, a vertical configuration of wire electrochemical discharge machining (W-ECDM) process with textured wire surface was used to machine the micro-slits on glass. The effects of process parameters like applied voltage, pulse on time, electrolyte concentration and feed rate were experimentally investigated on the size and geometry of micro-slits in terms of kerf overcut and straightness. The discharging mechanism for textured and smooth wire surfaces have been evidenced by the simulation results and high speed imaging. The simulation results revealed that the textured surface of wire electrode resulted in intensification of localized electric fields over the entire machining face of wire electrode. Thus, the breakdown of gas film from the textured surface of wire electrode generates spark discharges from the entire face of wire electrode. The underlying material removal mechanism of W-ECDM process during micro-slitting operation has been proposed and illustrated with appropriate schematics. Additionally, second-order regression models were developed to determine the relationships between input process parameters and responses. Features plots were used to correlate the response characteristics with respect to input process parameters. Desirability approach was used to optimize the parametric ranges for minimum kerf overcut and maximum straightness. The parametric combination of applied voltage of 48 V, pulse on time of 3 ms, feed rate of 3 mm/min and electrolyte concentration of 15% wt./vol. is recommended to machine the micro-slits with minimum kerf overcut of 105 μm and maximum straightness of 94.42%.