TAGUCHI-GREY OPTIMIZATION OF SURFACE ROUGHNESS AND MATERIAL REMOVAL RATE ON ELECTRO-DISCHARGE MACHINING OF NOVEL AA7075-TiO2 METAL MATRIX COMPOSITE USING WASTE CORNCOB BIOSILICA DIELECTRICS

In this study, a novel AA7075-TiO₂ metal matrix composite was machined utilizing a biosilica mixed EDM technique and the surface roughness and material removal rate are optimized. The biosilica particles are produced from waste maize cobs and then silane-treated. The optimization of process variables wasperformed using Taguchi grey relational approach with a process variable of peak current, gap voltage and pulse-on time. Results revealed that the gap voltage is the most important process variable, since it has a larger max-min difference of 0.25. In order to create a high MRR of 11.6$$mm³/min and a surface roughness of 2.25 m, the maximum GRG of 0.79 for Trial 1 (A2B1C3) represents the most ideal process variable group. The best results appear to be obtained with a peak current of 10 A, a gap voltage of 20$$V, and a pulse-on time of 140$$$\mu$s. The new GRG, however, is around 2.51% better than the anticipated optimized process variables of A2B1C3 with an old GRG of 0.79, according to the confirmation research. The new MRR of 11.89$$mm³/min and the surface roughness of 2.30$$s with a GRG of 0.81 are based on the optimized new process variables (A1B1C3).