Experimental investigation of the minimization of uncut fiber length in bidirectional CFRP drilling

Abstract

This research article investigates the minimization of uncut fiber length (UFL) in bidirectional carbon fiber-reinforced polymer (CFRP) drilling through experiments executed using a computer numeric control drilling machine and a titanium nitride-coated drill bit. The cutting conditions, such as the feed rate, spindle speed, and were varied to determine their effects on UFL. Three drilling setups were compared: dry machining, drilling using liquified nitrogen layers, and drilling using ice layers. The results showed that the use of ice improved hole quality and increased drilling efficiency by providing bottom support for the CFRP sheet sandwich, reducing delamination and fiber pull-out. Additionally, the feed rate, cutting speed, and drill geometry significantly influenced hole quality and maximum UFL. Overall, the study sheds light on the usefulness of cooling agents and bottom support for the modification of cutting parameters in bidirectional CFRP drilling.