An evaluation approach is presented to analyze the cutting force characteristics in cuttings of carbon fiber reinforced plastics using a flat drill. Because the cutting edges of the flat drill are parallel to the fiber layers, the cutting forces are measured for the fiber layers and bonding areas independently. The cutting forces were measured in drilling of three types of CFRP with unidirectional-, cross-, and quasi-isotropic-ply at a cutting speed of 100 m/min and a feed rate of 0.010 mm/tooth. The cutting force periodically changes in rotations of cutter, which is associated with the fiber cutting angles. The cutting forces in the fiber layers are nearly the same and the CFRP laminated structure has little influence on the cutting force. The thickness of the bonding effect area was estimated by the decrease of thrust force. The reduction of the cutting force depends on the fiber orientations laminated each other. The surface finish depends on the laminated structure changing in the depth of hole. The surface deterioration expands to the feed direction in drilling of unidirectional structure.
Watanabe et al. (Wed,) studied this question.