An unequal pitch ball-end milling cutter with micro-groove structure for suppressing CFRP milling chatter based on coordinated regulation of time delay effect and milling force

The chatter during milling significantly compromises the surface quality of thin-walled curved carbon fiber-reinforced plastic (CFRP) components. The vibration displacement among adjacent cutting edges during the machining process gives rise to a dynamic cutting thickness, which results in a delay effect. This delay effect is the primary culprit behind chatter. The strong anisotropy of the CFRP causes the dynamic cutting thickness change under the action of the time-varying fiber cutting direction, which intensifies the chatter. The more complex chatter behavior poses a new challenge to the high-quality milling of CFRP. This study understands that the delay effect and milling force are the main causes of additional damping, which leads to chatter. Based on this, a chatter suppression principle of coordinated regulation of time delay effect and milling force is proposed. Secondly, an unequal pitch ball-end milling cutter with a micro-groove structure is designed to give full play to this principle. By designing a large-span scheme of unequal pitch arrangement, the time delay effect is disturbed to destroy the root cause of chatter, and the micro-groove structure of the cutting edge is optimized to reduce the milling force. The surface milling experiment of curved CFRP workpieces was conducted using the designed cutter. The results show that the machining stability range of the cutter is greater than that of a conventional ball-end cutter. No chatter is observed when the process parameters are selected within the machining stability region for the processing of workpieces. The surface roughness of the workpiece in this experiment is less than 2.32 mu m.