Investigation of the Effect Mechanism of Cutting Sequence on Spiral Milling of CFRP/Ti Laminates Under Ultrasonic-Assisted Conditions

The hole-making mechanism of carbon fiber reinforced plastic (CFRP)/titanium alloy stacks is different from that of monolayer materials. In order to reveal the effects of different cutting sequence strategies on the hole-making quality and machining efficiency of the stacked materials, valuable insights are provided for the design of the stacking machining process and the selection of the most suitable cutting sequence. The researchers conducted ultrasonic vibration-assisted helical milling and conventional helical milling experiments with different milling parameters, and explored the basic influence mechanisms of CFRP -> Ti and Ti -> CFRP on the hole-making in both ways. The results show that different cutting sequences have significant effects on the axial force and chip morphology changes during CFRP/Ti stack machining. The dimensional accuracy and consistency of the holes cut from the Ti side are better, and the quality of the entrance and exit from the Ti side under the ultrasonically assisted condition is close to the quality level of the holes cut from the CFRP side under the normal helical milling, and the ultrasonically assisted condition plays a good role in improving the quality of the holes made. In addition, the tearing coefficients of CFRP hole entry/exit in both machining modes increased with the increase of feed per tooth in tangential direction and decreased with the increase of spindle speed. The tearing coefficients of entry/exit holes in CFRP direction were smaller than those in titanium direction.