New drill-milling tools for novel drill-milling process of carbon fiber-reinforced plastics

Process-induced damages, such as burrs and delamination, frequently occur and are the critical hole quality issues for CFRPs. These damages are strongly influenced by the axial cutting force. By employing the novel drill-milling process, the influence of the axial cutting force may be completely eliminated, and the process-induced damages can be remarkably removed. The drill-milling tools with a better performance are very critical to the drill-milling process. In this paper, according to the drill structure with V-shaped cutting edges and the mill structure with double-crossed helix flutes, two different new drill-milling tools are designed, and a series of tests are conducted on CFRPs. The result indicates that the influences of the cutting forces on the damages can be remarkably reduced during the helical milling phase by employing the drill-milling process. Under the same cutting conditions, the cutting forces of T2 are significant less than that of T1. The re-trimming effect of T2 is superior significant than that of T1 during the helical milling phase. The damages can be significantly reduced by using these two tools, especially by using T2 tool.