Experimental study and multi-objective optimization of near-dry wire-cut electrical discharge machining process

Abstract

Accompanying the development of modern manufacturing industries, the demand of machining special materials with complex profiles and shapes is now increasing. Most of these industries expect good performance of machine tools, best-quality products and high productivity. However, minimization of environmental impacts has also been an important role for the manufacturers all around the world, particularly after the introduction of ISO-14000 standards. In recent years, few research studies have been reported on the non-polluting ways to cut materials and have tried to meet good machining performance. Wire-cut Electrical Discharge Machining (WEDM) is a thermoelectric non-traditional machining process in which material removal takes place through the process of controlled series of spark generation in the small gap between a wire electrode and work material, which are separated by a dielectric medium. The dielectric medium plays an important role in the productivity and quality of the machined parts. Conversely, it is observed from the literature that the harmful substances were produced by thermal decomposition of liquid-based dielectric fluid during the cutting process. It is found in the available literature that the dry EDM process using the air or gas dielectric medium has the good environmental feedbacks with low machining performance. Trade-off between dry EDM process and low machining performance, it was found from the literature that the near-dry EDM process has always given moderate machining performance with very low environmental impacts. In this research, near-dry WEDM experiments have been conducted using the minimum quantity of demineralized water mixed with compressed air (air-mist) and oxygen gas (oxygen-mist) to improve the machining performance and to ensure the environment-friendly manufacturing process. A hydro-pneumatic circuit has been constructed to provide the air-mist and oxygen-mist dielectric mediums to conduct the experiments on existing liquid based WEDM machine.