Carbon fiber reinforced polymer (CFRP) composites have been widely used in aerospace, aviation, and automotive industries due to their high strength/stiffness-to-weight ratios, high temperature resistance and corrosion resistance. CFRP components are usually produced in near net-shape, and cutting operations such as drilling, slot milling, and edge trimming are required to remove excessive materials and fulfill the geometry and surface quality requirements of the final parts. Practical cutting operations are in the form of oblique and sequential cutting at the tool edge.

Different from metal cutting, the material removal mechanism and surface quality are highly dependent on the fiber orientation in cutting CFRP materials. This thesis presents a 3-D finite element model of oblique cutting of unidirectional CFRP. The effects of the fiber orientation and oblique angles on the chip formation, cutting forces, and subsurface damage are simulated and analyzed. It is found that the out-of-plane force and the depth of subsurface damage increase with the oblique angle in all fiber orientation angles except 0°. To represent the nature of sequential cutting, a second cut on the machined material with existing damages and residual stresses due to previous cutting is simulated. The results show that the effect of sequential cutting on the cutting forces is the largest at 90° fiber orientation angle.

Oblique cutting experiments were conducted on unidirectional CFRP. The cutting forces and chip morphology between the simulations and the experimental results were compared. The proposed FE model reveals the effect of oblique angle and sequential cutting on the mechanisms of chip formation and surface generation. The results are able to provide guidance in choosing proper cutting parameters and tool geometries to minimize the subsurface damage and potential delamination corresponding to in actual cutting operations of CFRP composites.