Towards understanding the material removal mechanism in multi-tooth milling of 2.5D C/SiC composites: numerical modeling and experimental study

Multi-tooth cutting is an effective method for materials machining with high quality and efficiency. To lay a foundation for the feasibility in multi-tooth milling of 2.5D C/SiC composites, combining with a new micro–macro scale numerical model and experimental analysis, the interaction mechanism and damage fracture mechanism between different fiber (0°, 90°, and Z-direction needling punched fiber) and multi-tooth scales mill are studied. Two main mechanisms resulting in fiber fracture are found, namely the extruding flexural fracture and micro-crack propagation fracture. The proposed numerical model is in good agreement with the experimental results in terms of fiber removal, chip forming, and surface topography. Specifically, fiber debonding and micro-crack propagation fracture occur in 0° fiber, and lamellar surface is produced. 90° fiber is mainly broken by shearing action and extruding bending. Correspondingly, the pits appear due to the fiber pulling out. Extruding flexural fracture occurs in Z-direction needle punched fiber, and peeling and lamellar surface is formed. Multi-tooth of the scales mill plays a repairing and grinding effect on the machined surface. And arc micro edge can restrain the formation of the fiber delamination and burr damage in particular. The study provides a new sight in low damage milling of 2.5D C/SiC composites.