Helical Milling of CFRP/Ti-6Al-4V Stacks with Varying Machining Parameters *

The hole-making process in stack materials consisting of carbon fiber reinforced plastics (CFRP) and Ti-6Al-4V remains a critical challenge. In this paper, an experimental study on the helical milling of CFRP/Ti-6Al-4V stacks was conducted by using two different machining strategies. Helical milling strategy I machines both materials with identical machining parameters, while machining strategy II uses two sets of machining parameters to machine each material. Helical milling performance was evaluated by the following indicators: tool life, cutting forces, hole quality (including diameter deviation, roundness, roughness, and hole edge quality). The results demonstrate that helical milling strategy II outperformed strategy I, leading to longer tool life (up to 48 holes), smaller cutting forces and better hole quality with higher geometric accuracy and smoother surface finish (Ra⩽ 0.58 μm for Ti-6Al-4V and Ra ⩽ 0.81 μm for CFRP), eliminating the need for reaming or de-burring.