Cutting edge—flatting and roughness measurement—to monitor blunting and chipping of the drill cutting edge when drilling CFRP

Tool wear is a major challenge when drilling CFRP. Cutting edge rounding quantifies the blunting of the cutting edge by considering the events happening in the flank–cutting edge–rake zone together by fitting a circle to this zone. The two interface zones, however, undergo wear in different ways. While the flank–cutting edge interface becomes rounded, the rake–cutting edge interface flattens out with drilling. Two new parameters, flank rounding (FR) and cutting edge flatting (CEF), are introduced to measure the damage to the flank and cutting edge, respectively. The nature of CEF and FR variation along the cutting edge shows that both are related. The chipping of the cutting edges is studied using a parameter called cutting edge roughness by monitoring the cutting edge topography. The progression of FR and cutting edge roughness along the length of the cutting edge shows that chipping may be related to the nature of FR progression. CEF could be easily measured using a simple measuring microscope and can be used to monitor drill wear.