The effect of differences in fiber sizes on the cutting force during the drilling process of natural fiber-reinforced polymer composites

This experiment aimed to analyze the impact of different fiber sizes on cutting forces during the drilling of Natural Fiber-Reinforced Polymer Composites (NFRPC) while also evaluating surface quality attributes, including delamination, fiber pullout, and overhanging fibers, influenced by variations in coconut fiber dimensions within the NFRPC material. The manufacturing process for composite panels utilized various methods, including hand layup for 200 mm long coconut fibers and composite casting for shorter fibers (2, 4, and 6 mm) mixed with polymer-epoxy. The results indicate that panels made from NFRPC with continuous fiber lengths of 200 mm exhibit higher cutting force values (253,650 N) compared to epoxy panels without fibers (235,288 N), suggesting that a significant force is required to sever the continuous fibers within the NFRPC. Conversely, the incorporation of short coconut fibers measuring 2, 4, and 6 mm reduces the cutting forces on the composite panels. However, excessive surface roughness in the final hole quality can be detrimental, primarily due to issues of delamination and fiber pull-out. • The experiment of different fiber sizes on cutting forces during the Natural Fiber-Reinforced Polymer Composites (NFRPC ) drilling process. • Surface quality aspects, including delamination, fiber pullout, and overhanging fibers, resulting from variations in the size of coconut fiber fibers within the NFRPC material observed. • NFRPC panels with continuous fiber lengths (200 mm) exhibit higher cutting force values compared to epoxy panels without fibers. This observation indicates that a substantial force is required to sever the continuous fibers running through the NFRPC panel. Additionally, severed fibers exhibit a significant number of fiber pull-outs around the hole. • The presence of short coconut fibers measuring 2, 4, and 6 mm in length leads to a reduction in cutting forces on the composite panels. Lower cutting forces are generally advantageous as they result in reduced power consumption, less tool wear, lower cutting temperatures, and improved surface smoothness. • It is noteworthy that surface roughness in the final hole's quality can be detrimental, primarily due to issues such as delamination and fiber pull-out. Excessive roughness, when applied, can contribute to fatigue failure and increased wear at the hole location.