A novel six-state cutting force model for drilling-countersinking machining process of CFRP-Al stacks

Drilling-countersinking (DC) machining is one of the most popular methods for making holes with countersink in modern industry. In DC machining process of carbon fiber reinforced plastics (CFRP)-aluminum (Al) stacks, the force caused by each cutting edge in different materials is changing all the time and will affect the quality of holes. This paper focused on the cutting force for DC machining of CFRP-Al stacks, developed a novel cutting force model, which can represent the dynamic cutting force at any time of the DC process. The whole DC process is divided into six different states which contain drilling, reaming, and countersinking in different materials. Forces on different cutting edges are modeled on the base of the microscopic oblique cutting theory. And the dynamic cutting forces of every moment in the six-state DC machining process are integrated on base of the integral limits analysis and equivalent fiber orientation. Experiments with different cutting parameters are developed to analyze the dynamic cutting force of CFRP-Al stacks. The trend of cutting forces according to different machining parameters is similar, and the influence of different cutting edge on the cutting force will change in different state according to the result of both experiment and proposed model. The values of cutting force getting from the experiments can match with the results of dynamic model well, despite the fact that gaps between different materials will affect the change of cutting force.