Experimental and numerical optimization study on CNTs/Al composites drilling based on response surface methodology

Carbon nanotube reinforced aluminum (CNTs/Al) composites have been widely used in the aviation field due to their excellent properties, but there are still problems in their drilling, such as unclear damage mechanisms and poor hole quality. This study investigates the removal mechanism of CNTs/Al composites during drilling by finite element simulation and single factor experiments, and the impact of process parameters on hole wall morphology and the quality of the entrance edge is revealed. Optimal process parameter combinations are determined based on the response surface methodology (RSM) and multiobjective optimization via the NSGA-II genetic algorithm, with method verification. The results show that during the drilling process of CNTs/Al composites, CNTs primarily experience fragmentation, rebound, and pull-out, while the Al matrix exhibits partial tearing and interfacial separation. The coating of the Al matrix and CNT agglomeration contribute to defects like burrs and microcracks. Entrance damage is notably more severe than exit damage, characterized by higher tearing factor values, longer side burrs, and increased trajectory scratch areas. The main process parameter that affects surface roughness and entrance tear is feed rate. The results of multiobjective optimization are n = 3830 r/min, f = 0.0674 m/min, h = 2.0558 mm, with Ra = 6.327 μ,m and L D 1 = 1.01732. Experimental validation shows Ra = 6.331 μm and L D 1 = 1.01743, with errors of 0.063% and 0.011%, respectively.