Realization of Surface Morphology and Process Parameter Optimization in MicroEDM Hole Drilling of Maraging Steel 300 Alloy

Abstract

The Micro-Electrical Discharge Machining, popularly known as micro-EDM, is a nonconventional machining process mainly used for producing micro features like micro holes, micro gears, micro moulds etc. that are difficult to be obtained by conventional process. It can machine different types of conductive materials especially the ones which are difficult to cut and machine. Microholes have been drilled using micro-EDM process on various alloys like Ti-6Al-4V, Inconel 718 etc. using electrodes like Copper, Tungsten etc. The parts produced by micro-EDM are widely used in micro-electro-mechanical systems (MEMS), biomedical applications, automotive industry, and defence industry. Selection and use of correct process parameters is of paramount importance for achieving superior surface quality and higher machining rates while performing micro drilling. However, this process has been characterized by low tool wear rate, low machining rate and longer machining time as compared to other non-conventional processes. This paper aims at studying the influence of various process parameters while drilling micro holes on Maraging Steel 300 alloy using a brass electrode. Maraging Steel 300 alloy is widely used in aerospace, tooling and machinery applications. Brass was selected as the electrode material so as to know its influence in the microdrilling process as it is known for achieving high material removal rate along with high wear ratio. Machining parameters considered in this work were pulse on time, pulse off time, tool diameter and current. A total of 27 micro holes of 300 μm, 400 μm and 500 μm were drilled on Maraging Steel 300 alloy as per the orthogonal array design based Taguchi methodology. Experiments were carried out on Toolcraft V04056 micro-EDM machine. Dielectric used was distilled water. The output responses observed were material removal rate, tool wear rate and overcut. Analysis was carried out using signal to noise ratio analysis. Material removal rate, tool wear rate and overcut were found to be influenced mainly by pulse on time and current. In order to know and better understand the surface morphology of the micro-holes, SEM micro-graphs were obtained. Presence of spatters and re-deposited eroded material were observed in few of the drilled micro holes. The results were verified by performing confirmation experiment at the obtained optimum combination. The confirmation results were in close proximity to the predicted results.