Design of discrete-edge polycrystalline diamond tool and its cutting performance in milling Cf/SiC composites

Abstract

Carbon fiber-reinforced silicon carbide matrix (Cf/SiC) composites are used extensively in many fields because of their superior properties, such as high specific strength and high specific modulus. However, Cf/SiC composites are typically difficult to machine materials due to their high hardness and anisotropy. Its machining easily leads to high cutting force, short tool life, and poor surface quality. The tool structure shows a significant impact on the cutting performance, which can further affect the cutting force and surface quality. In this study, a novel polycrystalline diamond (PCD) tool with discrete-edge structure was designed for milling Cf/SiC composites, which was devised with tiny microgrooves on the peripheral edge, and the geometric parameters were optimized by finite element simulation method. The cutting performance of the designed discrete-edge PCD tool in milling of Cf/SiC composites was studied. Cutting force, machined surface quality, tool wear mechanisms, and tool life were comprehensively investigated. Comparative experiments were also carried out with conventional straight-edge PCD tools by using identical cutting parameters. The cutting force when using the discrete-edge PCD tool gradually decreased with increasing cutting speed. The machined surface roughness Sa reached 3.5 μm at cutting speed of 125 m⋅min−1 with the discrete-edge tool. Surface defects in terms of fiber pullout, debonding, and cavities were reduced by the discrete-edge tool. The life of the discrete-edge PCD tool was 1.875 times that of the conventional PCD tool. The study illustrates that the cutting performance of the designed discrete-edge PCD tool is better than that of the conventional straight-edge PCD tool.