Understanding the effect of various Chip breakers’ configurations and feed rates in high-speed drilling of Ti-6Al-4V alloy

Abstract High-speed machining (HSM) has emerged as a compelling paradigm in modern manufacturing industries owing to its potential to enhance productivity, improve surface integrity, and reduce overall machining time. However, the application of HSM remains limited primarily due to constraints associated with conventional carbide tooling when machining difficult-to-cut materials such as titanium alloys. This study aimed to push the boundaries of high-speed drilling in Ti-6Al-4V by evaluating recently developed peripheral wiper and central stepped inserts, particularly evaluating the behaviors of different chip-breaker geometries in wiper inserts. Three distinct peripheral wiper inserts, featuring deep, medium, and shallow grooved chip breakers, are evaluated when operated at cutting speeds ( V c ) of 70 m/min and feed rates ( f r ) of 0.08 and 0.10 mm/rev. The dry cutting environment was used solely to evaluate the effect of feed rate and geometry during this HSM. This study presents a comprehensive evaluation of key performance indicators that cater to the demand of the aerospace industry, encompassing cutting tool life (CTL), surface roughness (Ra, Rt, and R z ), surface damage, diametric error, burr height, and microstructural changes. The findings revealed a maximum tool life of 20 holes when machining at a low feed rate of 0.08 mm/rev. Tool wear mechanisms were discussed in the context of sliding and seized regions, pointing out the coating delamination and build-up edge phenomenon. Additionally, the quantitative measurement of the crater was also presented, which was in the range of 145–150 μm. Machined surfaces were without voids and cracks, though minor scratches and feed marks were apparent at higher feed rates. The average surface roughness (Ra) values of drilled holes ranged from 1.2 to 2.4 μm with consistently oversized holes. Subsurface microstructural damage showed minor plastic deformation of grains extended to 10–15 μm along the cutting direction. The current study offers valuable insights and guidance for high-speed machining to boost the productivity of drilling Ti-6Al-4V. Furthermore, the inserts with deep grooved chip-breakers showed fracture at a higher feed rate, owing to a higher positive rake angle and a weaker cutting edge; hence, this tool configuration is not recommended for a high-speed regime.