CFRP (carbon fiber reinforced plastic) is widely used in aerospace field because of its excellent mechanical properties. Under the premise of ensuring the stiffness and strength of the aircraft

the application of CFRP can effectively improve the flight performance and reduce the weight of the aircraft

so as to achieve the purpose of energy saving and emission reduction

and improve the economic benefits of the aviation industry. CFRP is a typical difficultto-machining material

and in order to ensure that the structure has load-bearing capacity in different directions

CFRP multidirectional lamination is generally used in the aero-engine industry

which makes the anisotropy and inhomogeneity of the material more complex. In this paper

the milling fracture mechanism of CFRP unidirectional laminates and two kinds of CFRP multidirectional laminates is analyzed

and it is found that different fiber direction angles have great influence on the fracture mechanism during CFRP milling

resulting in different surface quality. Among them

bending fracture will lead to a sharp decline in surface quality

which should be avoided as far as possible

and the surface quality of bending fracture at different angles is also different. Based on this

an optimization method of tool cut-in angle in multidirectional CFRP milling is proposed

and the rationality of this method is verified by experiments. This method can effectively improve the machining quality of the first-stage composite fan blade of a certain engine.