Study on removal mechanism and surface quality in helical grinding 2.5D-C_f/SiC composites

Carbon fiber-reinforced ceramic matrix composites have excellent heat resistance and wear resistance, making them extensively utilized in the aviation and aerospace industries. However, processing carbon ceramics is challenging due to the inherent difficulty. Traditional hole-making methods often result in issues such as delamination and tearing during the processing of carbon ceramics. Helical grinding has emerged as a novel processing technology that shows promise for difficult materials like carbon ceramics. To address the lack of clarity regarding the removal mechanism and formation mechanism of material damage during helical grinding of carbon ceramic materials, firstly, this study models the trajectory and maximum undeformed chip thickness for a single abrasive. Subsequently, this study analyzes the influence of fiber anisotropy on the removal mechanism during helical grinding of carbon ceramics. The study also investigates the mechanisms behind exit damage occurring during carbon ceramic helical grinding processes. Finally, this study examines helical grinding technological parameters that affect surface quality by analyzing their impact on undeformed chip thickness. The results indicate that the matrix occurs brittle fracture during helical grinding. Four typical removal mechanisms emerge for different fiber angles: debonding is predominant at 0°; fiber fracture occurs at 45°; fiber shear occurs at 90°; fiber pull-out occurs at 135°. Hole exit damage is influenced by fiber direction with minimal damage observed when shear fracture occurs at angles 45° and 90° while burrs phenomenon and tear phenomenon are prevalent at angles 0°and 135°, respectively. By increasing orbital rotation speed and spindle speed or decreasing feed pitch, surface quality improved. Grinding parameters significantly affect surface quality by changing undeformed chip thickness and surface residual height.