Performance evaluation of novel chamfered inserts in high-feed turning of Ti-6Al-4V alloy

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The present work aims to investigate the performance of recently designed chamfered inserts in high-feed turning of Ti-6Al-4V which is considered as the mainstream alloy for aerospace applications. So far, extensive experimental data has been published while turning this alloy using square-, round-, and rhombic-shaped inserts despite certain limitations associated with each insert design. Recently, a novel chamfer insert has been developed with an intention of combining the geometric benefits of aforementioned individual inserts into a single tool. The present work evaluates wear behavior and machining performance of this newly designed insert while turning Ti-6Al-4V without coolant under constant depth of cut of 1 mm at four levels of feed rate (0.14, 0.337, 0.45, 0.562 mm/rev) and three levels of cutting speed (55, 85, 110 m/min). For output responses of tool life and workpiece surface roughness, the novel chamfer inserts not only outperformed the conventional shaped tooling but more interestingly, they were seen to compete with much expensive PCD inserts. Flank wear was observed as the principle wear mode without any signs of crater formation. Chipping was evident at the lowest cutting speed (55 m/min) and low feed rate combinations (0.14 and 0.337 mm/rev). On the other hand, fracture was encountered when operated either at an intermediate cutting speed (85 m/min) with highest feed rate (0.562 mm/rev) or highest cutting speed (110 m/min) and medium to high feed rates (values ranging from 0.337 to 0.562 mm/rev). Workpiece surface roughness (Ra) values were within the range of 0.51 to 3.91 μm over the investigated regime of operating parameters. Strain-hardened layer that deepened up to 150 μm from the machined surface was observed without any microstructural damage.