Abstract
This review provides an integrated perspective on the drilling of natural fiber-reinforced polymer composites (NFRPCs), focusing on damage mechanisms, governing parameters, and mitigation strategies. Owing to their heterogeneous, anisotropic, and moisture-sensitive nature, NFRPCs are particularly susceptible to delamination, fiber pull-out, matrix cracking, and thermal degradation, which collectively compromise hole quality. Reported delamination factor values (Fd = 1.02–1.60) highlight the strong interdependence between material characteristics, cutting parameters, and tool geometry. From a materials standpoint, hybridization – natural–natural, natural–synthetic, or nanofiller-based – enhances mechanical performance and resistance to drilling-induced damage. Process optimization techniques such as Taguchi, RSM, GRA, TOPSIS, and ANN are critically compared; although ANN often reports high accuracy (R2 > 0.95), its superiority over RSM should be interpreted cautiously given the small datasets involved, while RSM retains advantages in interpretability and reliability. Coated carbide drills and advanced geometries significantly reduce thrust force, delamination, and surface roughness, while combined backing support and cryogenic cooling substantially lower damage severity. The novelty of this review lies in its unified framework connecting material design, machining parameters, tool engineering, and damage control, while emphasizing emerging trends such as volumetric damage assessment and intelligent modeling. Key research gaps are identified, offering a structured roadmap for sustainable, high-quality machining of NFRPCs.