Chatter stability and surface quality in milling of unidirectional carbon fiber reinforced polymer

•The milling force model and dynamic milling system of UD-CFRP were established.•The chatter stability of milling UD-CFRP was studied.•The influence laws of the chatter stability on surface quality were discussed.•A novel method for predicting surface quality of machined UD-CFRP was provided. Carbon fiber reinforced polymers (CFRPs) are typical difficult-to-machine materials. Due to their anisotropic material property, chatter and poor surface quality are easy to occur during machining. In this paper, the mechanical cutting force model and dynamic milling system model considering the anisotropy of unidirectional CFRP (UD-CFRP) were established. The cutting force coefficients and the edge force coefficients in the cutting force model were calculated as functions of fiber cutting angle. The cutting force model can accurately describe the variation laws of milling force in different fiber directions. The chatter stability of milling UD-CFRP was analyzed and the influence of the fiber direction on it was studied. The influence laws of the fiber directions and chatter stability on surface quality were discussed, and a variable related to cutting stability, chatter factor, was defined, which provides a novel method for predicting surface quality of machined UD-CFRP.