The influence of MoS ₂ lubricity on the secondary cutting performance of PCD micro-groove textured tools

Micro-textured cutting tools possess unique advantages in reducing cutting forces, lowering chip temperatures, minimizing tool wear, and improving machined surface quality. Nevertheless, the secondary cutting effect induced by micro-textures impairs texture integrity and aggravates tool wear. Hence, it is of great significance to explore evaluation approaches and suppression strategies for the secondary cutting of micro-textured tools. This paper presents a method to evaluate the secondary cutting effect of micro-textured tools based on the roughness of chip scratches, which is verified via experiments. In the tests, a femtosecond laser was employed to fabricate micro-groove textures with inclination angles of 0°, 30°, 60°, and 90° on the rake face of polycrystalline diamond tools, and MoS ₂ solid lubricant was filled into these micro-grooves. Dry cutting experiments were then carried out. Using scanning electron microscopy, laser confocal microscopy, and a hardness tester, the performances of conventional tools, ordinary micro-textured tools, and micro-textured tools with MoS ₂ solid lubricant were evaluated through a comparative analysis of the rake face morphology, chip roughness, and chip hardness, with particular attention to the relative magnitudes of these parameters among the three tool conditions. The results indicate that micro-groove textured tools with textures parallel to the main cutting edge exhibit weaker adverse effects. During cutting, MoS ₂ solid lubricant delivers good lubrication and friction reduction, further optimizing the overall performance of micro-groove textured tools. The hardness of chips generated by lubricant-filled micro-groove textured tools is 0.9% and 4.12% higher than that from plain micro-textured tools and conventional tools, respectively. Meanwhile, the roughness of chips obtained with MoS ₂ lubrication is 38.10% lower than that from tools with only micro-groove textures.