Role of spark energy and frequency on wire-EDM performances of Al-2Mg alloy and Al-2Mg/20 Al3Fe composite: a comparative study

The performance of wire-electric discharge machining (WEDM) method is inevitably affected by the electric spark. A comparative study is presented related to the influences of spark energy (SE, 1.68-8.40 mJ) and spark frequency (SF, 12.82-15.15 kHz) on machining responses of Al-2Mg/20 vol.% in-situ Al3Fe composite with respect to Al-2Mg alloy. Such comparison is scanty in the literature. Machining performances were measured concerning material removal rate (MRR), cutting speed (CS), and surface roughness (SR) apart from the morphological evolution of machined surfaces. Irrespective of machining condition (for instance, at SE of 5.04 mJ), composite exhibited lower CS (1.27 mm/min), MRR (4.20 mm(3)/min), and SR (4.42 mu m) due to the insulating effect of reinforcement than alloy (i.e. 1.70 mm/min, 5.81 mm(3)/min, and 4.82 mu m, respectively). For both alloy and composite, all three machining performances increased linearly with rising the SE and SF, although the influence of SE was more pronounced over SF. With increasing SE, the difference in the magnitudes of CS and MRR between alloy and composite widened, while the same for SR narrowed. Formations of micro-cracks, lumps of debris, craters, and re-solidified layers were observed more on alloy machining surface than composite; these features enlarged with increasing SE and SF.