Experimental investigation and multi objective optimization of near dry wire cut electrical discharge machining process using cryogenically cooled wire electrode

Abstract

Wire-cut Electrical Discharge Machining (WEDM) is a thermo-erosion advanced machining process in which cutting of material by continuous high-intensity electric sparks in the cutting gap between the wire electrode and work material. The dielectric medium plays an important role in cutting characteristics, such as material removal rate, surface finish, wire wear rate, the accuracy of cutting path, and profile complexity. Conversely, a literature study revealed that toxic substances were produced by the decomposition of a liquid dielectric medium in a high-temperature plasma zone. It was also revealed that dry WEDM experiments were tested by replacing liquid dielectrics with pressurized air and gaseous media to reduce environmental impacts. However, the dry process machining performance was not achieved in a significant way due to certain technical uncertainties. In the near-dry WEDM, the pressurized air with the minimum quantity of demineralized water (air-mist) has been used as the dielectric medium to gain the merits of both liquid and dry WEDM processes. It has also been observed in the literature that almost dry WEDM research is still needed to enhance cutting performance. newlineIn this research, near-dry WEDM experiments were first conducted using a cryogenically cooled molybdenum wire tool to improve the cutting characteristics such as material removal rate, wire wear ratio, and surface roughness with minimum environmental impacts. The new hydro-pneumatic system has been developed to supply air mist in the cutting area and has replaced the existing liquid dielectric supply unit. Pure molybdenum wire and Inconel 718 alloy were used for electrode and workpiece respectively newline