Surface integrity and acoustic emission characteristics during slot milling 3D carbon/carbon composites using superabrasive diamond grinding point

Abstract

This study mainly investigated the effect of machining parameters on surface morphology and defects in three-dimensional carbon/carbon ceramic matrix composites during slotting with superabrasive diamond grinding points. Specifically, it discussed the mechanisms of burr and uncut fiber formation based on the relationship between grinding and fiber directions. The experimental work was conducted under different spindle speeds and feed speeds, revealing that the poor machining surfaces and severe defects occurred at the minimum spindle speed (2000 rpm) with maximum feed speed (160 mm/min), and most uncut fiber defects occurred when the fiber cutting angle exceeded 90°. Acoustic emission (AE) signals were analyzed via signal processing techniques to capture the energy and frequency characteristics of slotting process under various machining parameters. Results indicated that spindle speed had a significant impact on the frequency band distribution of AE signals, while feed speed primarily influenced the stability of signal profiles. The material removal and tool wear mechanisms were examined through SEM micrographs of machined surfaces and grinding points, revealing that fiber debonding and fracture were the primary material removal mechanisms, and were highly dependent on the fiber cutting angle. Abrasive particles with relatively lower cutting velocity at the center of the grinding tool suffered severe damage/wear.