Evaluation of the performance of a PCBN tool in turning AISI D2 hardened steel in continuous and interrupted cutting

Important technological advances in the mechanical manufacturing industry have increasingly generated good results with the turning of hardened materials, using polycrystalline cubic boron nitride (PCBN) tools, mainly replacing abrasive processes. The ability to meet project requirements without the need for multiple processes translates into cost reduction and increased productivity. Tool steels play varied and essential roles in various industrial applications, such as dies and punches for forming and cutting. Improvements in the performance of cutting tools are crucial to withstand the severe tribological conditions of the turning process of hardened materials. In this context, this work aimed to evaluate the performance of a PCBN tool in turning quenched and tempered AISI D2 steel, both in continuous cutting and interrupted cutting conditions, in the finishing operation with dry machining. The surface roughness was evaluated in the parameters (Ra, Rt, and Rz), the wear suffered by the tools, their mechanisms, and the morphological analysis of the chips. Tests were carried out with different cutting speeds (60, 130, 200, and 240 m/min), maintaining a constant feed rate of 0.15 mm/rev and a cutting depth of 0.2 mm. The results indicated that the most evident wear was crater and flank in the continuous cut, while in the interrupted cut, there was the presence of chipping and catastrophic failure. Wear mechanisms, such as adhesion (attrition), abrasion, and diffusion, were prominently observed. Furthermore, the tests showed that the increase in flank wear did not necessarily result in an increase in surface roughness, and that the wear mechanism changed with the increase in cutting speed. In the continuous cutting condition, the tool achieved more satisfactory performance, especially at higher cutting speeds (130, 200, and 240 m/min). In interrupted cutting, there is a predominance of catastrophic failure mainly in the ranges of 60 and 130 m/min and better performance at 200 m/min within the ranges evaluated.