Abstract

In order to further improve the machining quality of a drilling tool for difficult materials, the main cutting edge of the tool is artificially polished by a grinding wheel. Both grinded and original drilling bits are used to make holes in carbon fiber-reinforced polymer (CFRP) plates, while the dynamic strain wave generated during the process is measured using a fiber Bragg grating (FBG) sensor. Experimental results show that the polished drilling bit can produce high-quality holes. The main cutting edge becomes "1+2" multi-cutting-edge mode, and therefore it can increase the blade strength and reduce the tool-chip contact length, thus it improves the wear resistance of the tool. In addition, the regular "groove" on the surface of the cutting edge makes the debris flow smoother. Interestingly, the dynamic strain wave measured when drilling with the polished bit tool shows to have two sharp and high-intensity spectral peaks around the drilling rotation frequency, while the hole quality is very high. On the contrary, using the new unpolished drilling bit leads to low quality holes and a monitored strain wave with a multipeak spectral response. This study aims at providing favorable reference conditions for improving the utilization of drilling tools.