Research on axial cutting force fluctuation and periodicity in helical milling of CFRP.

Carbon fiber-reinforced plastic (CFRP) is a widely used material in the aeronautical and aerospace industry. Hole-making operations on CFRP frequently generate hole-exit damages which are related to the axial cutting force. As an alternative hole-making process, helical milling presents several advantages when compared to conventional drilling process. In order to study the mechanism of hole-exit damages in helical milling of CFRP, the axial cutting force during cutting process should be investigated in advance. Although CFRP is known as a difficult-to-cut material just because of being composite and non-homogeneous, the impact of composite structure and non-homogeneity on the axial cutting force has rarely been considered in the published researches of helical milling. This paper aims to investigate the axial cutting force in helical milling of CFRP, considering the composite structure and non-homogeneity of workpiece. The detailed laminated structure of the CFRP workpiece was investigated and the experiments of axial cutting forces were carried out. The results show that a periodic and fluctuant axial cutting force is generated in helical milling of CFRP. The periodic fluctuation of the axial cutting force was verified to be related to both the composite structure and the deformation of uncut material. Then, a cutting model was built to explain the changing process of axial cutting force during cutting process. [ABSTRACT FROM AUTHOR]