Comparative Analysis of Burrs in UD-CFRP Composites Using Advanced Hole Machining Technologies

Machining of carbon fibre reinforced polymer (CFRP) composites is challenging due to their inhomogeneous and anisotropic structure as well as the strong effect of the carbon fibres on wear. Burrs are critical machining-induced macro-geometrical defects in the case of the machining of CFRP composites, which may lead to assembly difficulties. Nowadays, although novel hole-machining technologies reduce the likelihood of burrs occurring, these technologies are often more costly and require longer machining times. The current experimental study focuses on the analysis of burrs induced by advanced hole machining technologies (helical milling, tilted helical milling and wobble milling) and comparison with a conventional one (conventional drilling).A total of 32 experiments were carried out in a VHTC 5-axis machining centre using uncoated solid carbide end mills. Furthermore, these technologies are compared and discussed based on the burrs experienced and average material removal rate (AMRR). Experimental results show that conventional drilling caused the lowest amount of burrs, followed by wobble milling, tilted helical milling and helical milling. Even though wobble milling is one of the most advantageous technologies in terms of burrs, the AMRR of conventional drilling is twenty times larger than that of wobble milling, therefore, the further development of wobble milling is recommended.