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

摘要

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.