Analysis of Entry and Exit Hole Delaminations During Drilling of Jute/Palm Fiber Reinforced Hybrid Composites Using HSS Drill Bits

The purpose of this study is to explore drilling defects in hybrid jute/palm fiber composites and propose practical solutions for enhancing machining outcomes. This work is novel in its detailed analysis of delamination, fiber pull-out, and surface fluffing using HSS drills. The results reveal significant differences in delamination factors between the entrance (jute fibers) and exit (palm fibers) under varying machining conditions. Quantitative analysis reveals that optimal conditions for minimizing delamination occur at a spindle speed of 2388 rpm and feed rate of 0.04 mm/rev, achieving delamination factors of 1.121 (entrance) and 1.069 (exit). These findings emphasize the critical role of machining parameters in controlling drilling defects and improving the integrity of hybrid composite materials. Using Response Surface Methodology, predictive models identified feed rate as the dominant factor. Optimizing resin application improved structural integrity and reduced defects, offering experimental evidence for industrial applications in sustainable hybrid composite manufacturing.