Characterization of the cutting forces and friction behavior in machining UD-CFRP using slot milling test

The friction behavior in machining carbon fiber reinforced polymers (CFRPs) is associated with many responses relating to cutting forces and temperatures, such as machining quality and cutting tool longevity. In milling operation where the fiber cutting angle is constantly alternating with the rotation of the tool, it is quite difficult to establish the coefficient of friction compared to the case of homogeneous materials. By using slot-milling as an open tribosystem, this paper investigates the behavior of cutting forces in machining unidirectional CFRP using uncoated single flute milling tools with different rake angles (− 15, 0 and 15°) and estimates the coefficients of friction based on cutting force decomposition using a simplified two-region cutting model. The friction coefficient in slot milling of UD-CFRP was found to depend mainly on fiber cutting angle and mode of cutting, i.e., up milling vs. down milling. The peak friction coefficient occurred at fiber cutting angle of 115°. The effect of rake angle on the cutting forces was most profound in the shearing region of the cutting model, but has no significant effect on the frictional forces.