Understanding the effects of grinding speed and undeformed chip thickness on the chip formation in high-speed grinding

This paper carries out a finite element (FE) analysis to investigate the effects of grinding speed (20 ∼ 400 m/s) and undeformed chip thickness (1 ∼ 8 μm) on chip formation during single grain grinding of nickel-based superalloy Inconel 718. Three factors related to the Johnson-Cook (J-C) constitutive model, i.e., the strain hardening, strain-rate hardening, and thermal-softening, were taken into account to determine the critical grinding speed. The results show that the chip segmentation frequency increases linearly with increasing the grinding speeds. It was found that the critical grinding speed is 150 m/s based on the variations of equivalent plastic strain, von Mises stress, and grinding force. It was also revealed that the effects of strain hardening and strain-rate hardening on the chip formation are more significant than that of the thermal softening when a grinding speed is below 150 m/s. However, if the grinding speed exceeds this critical value, thermal softening becomes a dominant factor.