Effect of drilling process parameters on agro-waste-based polymer composites reinforced with banana fiber and coconut shell filler

The present study effectively employed agro-wastes in the fabrication of novel hybrid polymer composites, incorporating banana fibers (BA) and coconut shell (CS) fillers. The machining performance of the hybrid composites was assessed in relation to the effects of drilling process parameters. CNC drilling was conducted under the following conditions: coconut filler content (1%, 3%, and 5% by volume), feed rates (50, 75, and 100 mm/min), and spindle speeds (1000, 1500, and 2000 rpm). A drilling experiment was carried out using a Taguchi L27 orthogonal array, and the responses, including thrust force, peel-up delamination, and push-out delamination, were analyzed in detail. The minimum thrust force was achieved with 5 vol.% coconut shell filler, a feed rate of 50 mm/min, and a spindle speed of 2000 rpm. The lowest peel-up delamination was observed with 1 vol.% coconut shell filler, a spindle speed of 1500 rpm, and a feed rate of 100 mm/min, while the minimum push-out delamination occurred under the same filler content, a spindle speed of 1500 rpm, and a feed rate of 75 mm/min. Fiber/matrix debonding, fractured fibers, and matrix cracks were identified as critical failure mechanisms through scanning electron microscopy.