Impact of different parameters in the drilling of CFRPs with nanocrystalline diamond coated tools

The drilling process of composite materials, such as the carbon fiber reinforced polymer (CFRP), constitutes a challenging task due to their inhomogeneous and anisotropic characteristics, besides the highly abrasive wear behaviour of their fibers. Accordingly, machining parameters should be carefully studied to optimize the process, leading to a better surface quality (avoiding defects in the CFRP) and to a lower wear behaviour of the cutting tool. This study proposed to test the drilling of a CFRP with a thermoplastic matrix using two different tool geometries (conventional and double-point angle drill) and varying two parameters, feed (f) and spindle speed (n), each one with two levels. It was concluded that the double-point angle drill with lower spindle speeds generates lower thrust force and torque values, as well as better hole quality. Higher spindle speeds combined with lower feeds result in fractured chips, in contrast with continuous chips for the other combinations.