Influence of machining parameters on cutting performance and failure mechanisms of coated carbide tools

Abstract

Machining performance is significantly influenced by friction at the tool workpiece interface, chip removal rate and cutting temperature. In coated carbide tools, the coating functions as a solid lubricant to enhance wear resistance and to reduce friction and heat during the cutting process. This study aims to determine the optimal machining parameters for improved cutting performance and to characterize the coating and substrate materials of coated carbide tools. The machining parameters were established through an experimental design of cutting conditions to evaluate cutting performance and to characterize the behavior of coated carbide tool layers under mechanical, thermal and chemical interaction using microanalysis. Under mechanical loading, machining aluminium 6061 (Al-6061) resulted in abrasive wear of 0.07 mm, whereas AISI 1070 exhibited more severe edge wear of 0.25 mm. Under thermal loading, a 20% increase in cutting speed produced edge wear of 0.10 mm for Al-6061, while AISI 1070, at a 20% reduced cutting speed, exhibited flank wear and plastic deformation of 0.16 mm. Chemical interaction analysis conducted at a cutting speed of 385 m/min, feed rate of 0.15 mm/rev, and cutting depth of 1.5 mm during the initial wear stage (tc 1.74 min; VB 0.07 mm) in machining Al-6061 revealed no coating delamination. A further 20% increase in cutting speed (462 m/min; VB 0.10 mm) confirmed stable coating integrity without observable delamination. In contrast, machining AISI 1070 at a cutting speed of 111 m/min, feed rate of 0.15 mm/rev, and cutting depth of 1.5 mm during the initial wear stage (tc 1.1 min; VB 0.25 mm) resulted in dominant abrasive wear accompanied by partial loss of the diamond film coating, thereby exposing the substrate. Microanalysis under a 20% reduction in cutting speed (89 m/min; VB 0.16 mm) indicated that the diamond film elements accounted for approximately 35% of the detected composition, while the single layer diamond film experienced a volume reduction of about 64%; however, no coating delamination was observed. The results demonstrate that mechanical, thermal and chemical interaction did not induce coating delamination in coated carbide tools. Conversely, the dominant wear mechanism is gradual abrasive wear, leading to the progressive loss of the diamond film layer from the carbide tool substrate.