Cutting forces and correlation with the damages during CFRP drill-milling by using novel drill-milling tool

During CFRP hole-making, exit damages such as burrs and delamination frequently occur. To adequately eliminate the influence of the axial force on the damages, a new combined drill-milling process was proposed. But the details of the cutting forces and the undeformed chip geometry in the helical milling phase for special drill-milling tool have not yet been comprehensively described and analyzed. Theoretical and experimental analyses of the drill-milling cutting forces and the performance of the novel drill-milling tool are investigated. The results indicate that the helical milling parameters significantly affect the undeformed chip transverse areas as well as the cutting forces. During the drilling phase, the exit tears and delamination can be observed, but few exit burrs can be left. During the helical milling phase, the drilling-induced damages can be further reduced even removed completely. The cutting forces Fx and Fy increase up to 15.9% and 22.6%, respectively, when ng increases from 60 to 180 rpm. When e increases from 0.1 to 1.3 mm, Fx and Fy increase up to 69.9% and 44.4%, respectively. Fx and Fy increase up to 40.3% and 35.2% respectively, when vf increases from 6 to 24 mm/min. But Fx and Fy decrease up to 18.0% and 10.4% respectively, when nz increases from 2000 to 5000 rpm.