Aramid fiber-reinforced plastic (AFRP) is widely used in bullet-proof and armor structures, and is difficult to drill because of the high-toughness aramid fibers with ductile fracturing—differently from carbon fiber. Therefore, drilling quality cannot be ensured by the drilling used for carbon fiber-reinforced plastic, and frequently, delamination and burrs occur in the drilling process. This article first established a two-dimensional cutting model for analyzing the fiber deformation and material interface cracking. According to the model, reducing the thrust force and the radial force of the edge on the fibers is an effective way to reduce the fiber deformation, and a three-point step drill is proposed further. Comparative experiments were carried out among twist drilling, candle core drilling and three-point step drilling under three drilling parameters. The results show that the three-point step drill changed the traditional cutting behavior on the drill-exit material into a compound process. Finally, the AFRP was cut effectively with the novel drill with a small thrust force, and the delamination and “burrs area” were reduced through different drilling parameters. In summary, the three-point step drill can drill the AFRP without delamination and burrs with 0.02 mm/rev, which provides a new solution of cost-effective production for AFRP manufacturers.

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Carbon fiber reinforced plastic/polymer is popular for aerospace structures and these structures require milling with desired configuration and integrity within strict damage tolerance. However, due to the influence of cutting thrust force on the surface materials when milling carbon fiber reinforced plastic/polymer, it is easy to cause surface damages. This article aimed to study the effect of cutting thrust force direction and size on the damages and guided the suitable milling tool and cutting parameters, further to propose a milling method with low damages. The two-dimensional cutting model was established successfully for analyzing the tool–composite contact and the fiber–plastic/polymer interface crack. Based on the model, the cutting direction forward inside and small cutting force are the ways to avoiding the burrs and tears. The thrust force was the main concentrated force causing the damages in milling, so the left–right edge milling tool was proposed to realize cutting fibers to inside for both surfaces. Besides, small feed per tooth is an effective way to reduce the force. Therefore, the left–right edge milling tool with small feed per tooth is low-damages method. Comparative milling experiments are carried out to verify the method, from the result, the burrs, tears and delamination are effectively inhibited.

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