A semi-empirical model to predict material removal rate during air-assisted electrical discharge machining

Abstract

The present study is focused on exploring the use of air-assisted electrical discharge machining (AAEDM) of high carbon high chromium die steel. One of the notable drawbacks of conventional EDM machining is low material removal rate (MRR). So, there is a critical need to evolve a method that can increase the MRR of conventional EDM process. This experimental study is focused on the use of compressed air in die sinking EDM, under controlled machining conditions to evaluate MRR. The influence of process parameters, viz., discharge current, pulse on time, duty cycle, tool rotation and discharge air pressure, on MRR has been investigated. ANOVA has been performed to select the significant factors affecting MRR. An effort has been done to establish a semi-empirical model to predict MRR in AAEDM process of high carbon high chromium die steel using dimensional analysis. The experimental and predicted values through semi-empirical model are found to be in accord with each other. The surface morphology analysis has been performed by using scanning electron microscope for machined specimens. The energy-dispersive X-ray spectrometer analysis has been used to investigate the material removal mechanism in AAEDM process.

Electric discharge drilling with gas-assisted multi-hole slotted tool

“…This improved the removal rate and also reduced the amount of liquid material re-to the surface. Kunieda et al [23] and Singh et al [27] have also reported similar findings.…”

“…, where "r" is the plasma radius and "l" be the inter-electrode gap existed at applied gap voltage. It can be concluded from the above mentioned relationship that the density of the spark energy increased with an increase in the discharge current [32].The oxygen in the air induces an exothermic reaction that produces additional heat for material removal in AAEDD [27]. The molten metal of the steel workpiece reacts with oxygen from the air and releases heat.…”

Experimental investigation and statistical modeling of air-assisted EDM of Al–SiC composite with an improvised tool

“…This improved the removal rate and also reduced the amount of liquid material recast to the work sample. Kuineda et al [36] and Singh et al [37] have reported similar findings.…”

“…As the AAEDD process is used, the exothermic reactions between the air supplied by the multi-hole electrode and the molten metal release extra heat apart from the heat provided by the spark, which induces further melting and evaporation of the materials [17,32]. The gaseous dielectric flow from the electrode produced more turbulence and cavitation and extracts the eroded materials from the interelectrode gap [37]. However, the limited clearance of gas flow results in the inadequate removal of the eroded matter [25].…”

“…15, one can see that the roughness of the surface increases with an improvement in the peak current. This change may be attributable to broader and deeper discharge craters as the peak current rises [15,37]. Besides this, an enhancement in the peak current forms micropores due to the poor durability of the composite [5].…”