Drilling study on CFRP/Ti-6Al-4V stacks using chip breaker grooved drill

Carbon fiber reinforced plastic/Ti-6Al-4V stacks are most commonly utilized in aircraft structures as they have a higher strength-to-weight ratio. Usually, these materials are stacked together and riveted by drilling holes. The holes produced during the operation require more precision and high quality. In general, the chips produced during the drilling of Ti-6Al-4V alloy stacked underneath the surface of CFRP material increase the damage and thrust force during drilling CFRP/Ti stacks. In this experimental investigation, a chip breaker in the form of a groove was machined on the rack face of the drill tool. Sixteen drilling experimental runs were conducted on CFRP/Ti-6Al-4V stacks along with standard and grooved tungsten carbide drills. Two input parameters such as cutting speed and feed with four levels were considered during drilling under a dry machining environment. The response attributes measured were thrust force, chip formation and delamination. Based on the study, a decrease in cutting force with an increase in the chip breakability was found at maximum speeds. Furthermore, a significant decrement was noticed in the delamination and formation of burrs with the grooved drill tool compared to the standard tool.