Surface and subsurface investigation of Al-Mg-MoS2 composite on performing wire electrical discharge machining

Abstract

Metal matrix composites (MMCs) give challenges during machining because of the reinforcements present in them as this ultimately leads to increased tool wear and a poor surface finish. Considering this, Al-Mg-MoS2 composite samples prepared using powder metallurgy process are employed under unconventional machining process like wire electrical discharge machining (WEDM), since the composites prepared to possess a higher hardness and strength compared to that of pure aluminium. The machining is done under 3 different factors operated at 3 levels, peak current (10 A, 15 A & 20 A), pulse on time (60 μs, 90 μs & 120 μs), and gap voltage (40 V, 45 V & 50 V) to analyze the material removal rate (MRR), surface roughness (SR) and overcut (OC). The surface texture of the machined samples is analyzed with scanning electron microscopy (SEM) and the recast layer so formed has also been analyzed. It is detected that the recast layer is found larger for larger surface roughness due to the higher spark energy at high-level peak current. Also, an optimal parameter of 15 A peak current, 45 V gap voltage and 90 μs pulse on time and 4% of MoS2 is determined through main effect plots for better machinability of the samples to obtain a better MRR, SR and OC. A better MRR, an improved surface finish and a reduced OC is seen in Al − 4%Mg - xMoS2 composite samples than that of pure Al and Al − 4% Mg materials.