Material identification method for helical milling of CFRP/Ti stacks based on torque−speed model

Because of the excellent material properties of carbon fiber reinforced plastic composites (CFRP) and titanium alloy (Ti), CFRP/Ti stacks are widely used in the aerospace industry. As the foundation for connecting the above two materials, the integrated hole making process of CFRP/Ti stacks has become an important work in aerospace assembly. Due to the limitations of the huge difference in machining performance between the two materials, the applicable processing parameters of each layer material are different. In addition, the stacking order and thickness may be inconsistent at different locations, which makes it difficult to identify the material and set the corresponding processing parameters. In this paper, a material identification method for helical milling of CFRP/Ti stacks based on the torque-speed model is presented to solve these problems. Torque prediction model is established for helical milling of CFRP and Ti, then the function of torque with respect to spindle speed is resolved. Meanwhile, the torque-speed model of pneumatic spindle is proposed based on the self-developed portable helical milling equipment. The predicted speed of equipment when processing different materials is solved by associating the above models, thus establishing the corresponding relationship between the spindle speed and material for material identification. Validation experiments were carried out and the results substantiate that the torque prediction model has good accuracy. Furthermore, the measured speed of two materials are highly consistent with their respective predicted values, which indicated that the proposed method can effectively identify the material types and provide a theoretical basis for subsequent processing.