Bi-directional milling hole machining process based on novel biomimetic cutting tool: Used to reduce delamination damage of aramid fiber-reinforced polymer

Aramid fiber-reinforced polymer (AFRP) is anisotropic and super tough, as a result, machining defects such as long burrs and material delamination are easily produced during the hole-making process. In order to effectively inhibit the delamination damage of AFRP, a new bionic tool structure was designed based on the tooth profile morphology of the beetle mouthparts, and comparative tests of different types of tools were conducted. On this basis, a bi-directional milling hole-making method is proposed based on the orifice delamination damage mechanism of AFRP, and the evolution of material damage under different milling depths is explored. The experimental results show that the new bionic tool changes the removal behavior of material in the cutting machining process of traditional tools and can reduce the cutting force while suppressing delamination damage. In the feed speed range of 30 − 80 mm / min , the cutting force size was 26.953 % of that of the milling cutter and only 21.677 % of the drill. Under the bi-directional milling conditions, the quality of AFRP orifice machining was significantly improved, and the degree of delamination damage was reduced by 13.243 % compared with the conventional milling conditions, which achieved the expected cutting effect. It was found that the hole wall material in the bi-directional milling process provided some support and could significantly increase the critical axial force in material delamination, which was about 3.797 times that of the conventional milling process. In conclusion, the research results in this paper aim to achieve the deterministic machining goal of high-quality cutting of composite materials.