Enhancing the Machinability of Basalt Fiber-Reinforced Composites Through Innovative Drill Design and Material Modification

Basalt fiber-reinforced composites (BFRCs) are highly regarded for their strength, thermal stability, and chemical resistance, making them ideal for aerospace, marine, and automotive applications. However, challenges such as fiber pull-out, matrix crack, delamination, and tool wear during drilling can affect structural integrity and increase production costs. Addressing these challenges, this study explores the drilling performance of basalt fiber-reinforced composites (BFRnCs) with halloysite nanotube (HNT) reinforcement under various machining conditions. Two types of drill bits, including a novel chip cutter drill, were employed to evaluate thrust force, delamination, surface roughness, and damage mechanisms at different cutting speeds and feed rates. The results demonstrate that HNT reinforcement significantly enhances the fiber-matrix interface and reduces damage during drilling. Notably, at a cutting speed of 100 m/min, the thrust force decreased by 23.5% in HNT-reinforced samples compared to non-reinforced composites, when using the chip breaker drill. Furthermore, the surface roughness values were consistently lower with the novel drill bit, decreasing from 5.15 µm to 4.99 µm for BFRnC samples at high feed rates. The delamination factors were minimized under optimized conditions by up to 14.5% in BFRnCs. Additionally, the chip breaker drill significantly minimized fiber pull-out and delamination, especially at higher cutting speeds. These outcomes underscore the critical role of material modification and drill geometry in enhancing the machinability of advanced composites, offering valuable insights for enhancing drill performance in high-performance industries.