Investigation on surface micro-crack evaluation of engineering ceramics by rotary ultrasonic grinding machining.

Rotary ultrasonic grinding machining (RUGM) is regarded as the most powerful machining method for engineering ceramic. However, there are micro-cracks on the machined surface inevitably for lower fracture roughness of material. As part of surface integrity, effective parameter and unified criterion are not proposed for micro-crack evaluation. In the paper, surface micro-crack evaluation of engineering ceramics by RUGM was investigated. Micro-crack generation area ratio calculation model and information dimension calculation model were established. On the basis of those, a new evaluation parameter, called micro-crack fractal density, was proposed to reveal the characteristics of micro-crack. The parameter was proved to evaluate micro-crack evolution rule effectively with the advantages of statistics and multi-scale. Meanwhile, the factors affecting micro-crack fractal density evaluation were investigated. It is found that the micro-crack fractal density increases with cutting force rising, while it decreases as fracture toughness rises. The results provide the support for surface integrity evaluation of engineering ceramics. [ABSTRACT FROM AUTHOR]