Drilling behaviour of kenaf fiber reinforced plastic composites: Effect of fiber orientation angle and drilling parameters

In this study, the drilling performance of kenaf fiber reinforced plastic (KFRP) composites with fiber orientations of 0°/90°, 30°/−60°, and ±45° was experimentally investigated. The composites were manufactured using the vacuum infusion method and mechanically characterized through tensile tests to support the interpretation of machining behaviour. Drilling experiments were carried out under different spindle speeds and feed rates to evaluate their effects on cutting force, temperature, and delamination factor. The results showed that the 0°/90° fiber orientation exhibited the highest tensile strength, while the ±45° configuration showed the lowest, reflecting the influence of fiber alignment on load-bearing capability. During drilling, cutting forces decreased with increasing spindle speed and increased significantly with feed rate, with feed rate identified as the dominant parameter. The 30°/−60° orientation resulted in the lowest thrust force and temperature values, whereas the ±45° orientation exhibited the highest thermal and mechanical responses, which corresponded to higher delamination factor. Statistical evaluation using analysis of variance (ANOVA) confirmed the significant effects of fiber orientation, spindle speed, and feed rate on cutting force, temperature and delamination factor.