Mechanism of cutting damage formation and turning process optimization of 3D needled C/SiC composites

Abstract

This paper investigates the damage mechanisms of 3D needled C/SiC composites through finite element method analysis and orthogonal turning experiments using polycrystalline diamond (PCD) tools. The results show that material can be removed in a fragmented manner due to its brittleness. The SiC ceramic matrix fractures earlier than the carbon fibers, leading to cracks along the fiber-reinforcement direction and machining surface defects that are primarily characterized by matrix cracking, fiber fracture, fiber pull-out, and microcracks. Chips resulting from the fracture of carbon fiber bundles are typically elongated and flat, whereas those containing SiC ceramic matrix are irregularly block-shaped, with cracks present on their surface. The optimized turning parameters were found to be – a spindle speed of 200 r/min, a feed rate of 0.15 mm/r, and a cutting depth of 0.1 mm, which led to a 50.38 % increase in material removal rate compared to current turning process parameters.