Experimental investigation of powder-mixed electric discharge machining of AISI P20 steel using different powders and tool materials

PurposeThe purpose of this paper is to investigate the performance of powder-mixed electric discharge machining (PMEDM) using three different powders which are aluminium (Al), silicon carbide (SiC) and aluminium oxide (Al2O3). Besides that, the influence of different tool materials was also studied in this experimental investigation. Hence, the work material selected for this purpose was AISI P20 steel and tool materials were copper, brass and tungsten. The performance measures considered in this work were material removal rate (MRR), tool wear rate and radial over cut (ROC).Design/methodology/approachThe process variables considered in this study were powder types, powder concentration, tool materials, peak current and pulse on time. The experimental design, based on Taguchi’s L27orthogonal array, was adopted to conduct experiments. Significant parameters were identified by performing the analysis of variance on the experimental data.FindingsBased on the analysis of results, it was observed that copper tool combined with Al powder produced maximum MRR (58.35 mm3/min). Similarly, the Al2O3powder combined with tungsten tool has resulted least ROC (0.04865 mm). It was also observed that wear rate of tungsten tool was very low (0.0145 mm3/min).Originality/valueThe experimental investigation of PMEDM involving three different powders (Al, SiC and Al2O3) was not attempted before. Moreover, the study of influence of different tool materials (Cu, brass and W) together with the different powders on the electric discharge machining performance was very limited.

Micro-Hardness Study on AISI P20 Steel Using Taguchi Method

A well-designed experimental were conducted with L18 Orthogonal Array (OA) based on the Taguchi method with input factors discharge current, pulse on time, lift time and flushing pressure. Micro hardness was measured and the mean of the observed values were plotted. The factors effecting the micro-hardness of the work-piece has been obtained. It is inferred that micro-hardness value increases with increase in discharge current and decreases with increase in Pulse on Time. The optimal condition for minimum hardness was found to be discharge current (Ip) = 2A, pulse on time (Ton) = 500μs, lift time (Tup)= 1.4 ms and flushing pressure (Fp)= 0.2 kgf/cm2.