The DD407 single crystal Ni-based superalloy with a face-centered cubic structure exhibits strong anisotropic characteristics. In order to reveal the material chip formation mechanism and the impact effect of crystal orientations on the materials’ milling machinability, a combination of experimental observations and theoretical analysis were applied in this study. Considering the resolved shear stress and slip system theories, a fundamental theoretical explanation of the milling force and surface quality along different crystal directions on the (001) crystal plane of the DD407 single crystal Ni-based superalloy was proposed based on a previously constructed anisotropic milling model. Our work in this research verifies that [110] crystal direction on the (001) crystal plane of the DD407 single crystal Ni-based superalloy is the most optimal feeding direction during milling, taking into account surface roughness and morphology, slot bottom plastic deformation, work hardening, and chip edge burr feature.

Carbon fiber-reinforced polymer composites are widely used in aviation and aerospace applications due to their excellent mechanical properties. Numerous studies have focused on tool wear at extreme machining parameters (f ≥ 540 mm/min) to accelerate tool wear experiments. However, using mild machining parameters is also instructive for current process production. To investigate the effect of wear on the surface integrity of CFRPs under mild parameters, a tool wear experiment on CFRPs was carried out at a conventional feed rate (f = 60 mm/min). The results show a cutting temperature increase of 47%, a cutting force increase of 53% and a flank wear width increase of 282% for PCD tools (with mild milling parameters) from 0 to 100 m of cutting length. As the cutting temperature reaches the glass transition temperature, Tg, during the stable wear stage, severe burrs and a large number of cavities appeared on the groove, and the subsurface with granular wear on flank wear land due to the transform of the matrix. Furthermore, Ra and Rz exhibit good indicators of cutting length and subsurface damage.