Hybrid High-Power Laser and Mechanical Drilling of Thick CFRP Laminates

Abstract Thick carbon fiber-reinforced polymer (CFRP) composites are extensively used in the aerospace industry, but conventional mechanical drilling often results in burrs, delamination, and significant tool wear. Laser processing introduces heat-affected zones (HAZs) and taper, while pulsed laser trepanning combined with mechanical drilling lacks efficiency for small holes in thick CFRP. This study proposes a high-power laser-mechanical hybrid drilling process, integrating short-duration high-power laser punching with mechanical drilling to reduce defects and tool wear. The study was conducted on 34.6 mm-thick CFRP laminates. Comparative experiments revealed that high-power laser processing with higher energy density achieved greater processing depth within a shorter duration, while minimizing heat accumulation and reducing sensitivity to focal position variations. HAZ dimensions and taper angle could be effectively controlled through laser parameter optimization. Compared with conventional mechanical drilling, the laser-mechanical hybrid drilling approach demonstrated superior performance: The preliminary laser-generated HAZ approximating the target aperture size resulted in a 32.4% reduction in tool temperature and a 42.4% decrease in cutting force. This methodology significantly mitigated machining-induced defects including burrs and delamination, while achieving 38.8% and 64.66% reductions in flank wear and primary tool wear, respectively.