Influence of Cutting Heat on Quality of Drilling of Carbon/Epoxy Composites

Cutting heat generated during drilling of carbon/epoxy composites has been recognized as a factor to influence the machine quality. This research aims to study the damage induced by cutting heat during drilling. A temperature-dependent experiment was carried out. The temperature of specimen was changed, and the machine parameter was constant in the experiment. The material temperature near exit was measured. Besides, the machine quality was detected, and the failure mode of the machined surface was observed. The results show that the decrease of material stiffness with increasing temperature induces the decrease of machine quality. Furthermore, delamination, transverse crack, high porosity, and fuzzing are mainly caused by low material stiffness. The transverse cracks which join together under cutting force lead to the generation of spalling on exit surface. As temperature increases, the failure modes of the machined surface changes from matrix dominant failure to interface dominant failure. It is predicted that the critical material temperature of damage-free is 186 degrees C.