Investigation on hole quality in drilling of thermoplastic GF/PEEK composite using twist and double-angle-tip drills

Glass fiber reinforced polyether ether ketone (GF/PEEK) composites have been widely used in engineering manufacturing fields due to their excellent mechanical and thermal properties as well as recyclability. This study aims to investigate the drilling quality of GF/PEEK composites under varying machining conditions. Drilling experiments were carried out using twist drill and double-angle-tip drill to evaluate the effects of drilling parameters and drill geometry on drilling temperature, thrust force, as well as exit and hole wall morphology. The results show that compared with the twist drill, the thrust force and drilling temperature generated by double-angle-tip drill were reduced by 32% and 15%, respectively. The double-angle and outer-edge drill tip of the double-angle-tip drill resulted in less delamination and burr formation. SEM analysis further revealed that the double-angle-tip drill produced finer and smoother hole wall than the twist drill. These experimental findings provide valuable guidance for achieving low-damage drilling of thermoplastic composites.