A study on micro-machining spinel by applying ordinary cutting and ultra-sonic elliptical vibration cutting

摘要

Magnesium aluminate spinel (MgAl2O4) ceramic, due to its outstanding optical and mechanical properties, has become a promising material of optical components. However, as a hard and brittle material, spinel is difficult to generate high surface integrity with traditional machining methods. To this end, elliptical vibration-assisted machining (EVAM) has been developed and proved an effective way of machining some typical hard and brittle materials with increasing ductile-to-brittle transition (DBT) depth and machining quality. In this paper, ordinary cutting and elliptical vibration-assisted (EVA) cutting methods were tested on spinel ceramic in a comparative study. Two models for predicting critical depth of cut in EVA cutting were developed by incorporating the elliptical cutting locus. Circular plunge cutting test was performed on the as-polished spinel samples with different machining parameters. The results of the measured DBT depths indicated that EVAM could significantly increase the critical depth of cut when machining spinel which was corroborated by the developed theoretical model. Besides, the analysis of groove topography revealed that the material removal mechanism of ordinary cutting and EVA cutting was significantly different. It is concluded that the overlapped circulating-cutting is responsible for the increased critical depth and improved surface quality. The proposed models provide a new approach for the determination of critical depth of cut for ductile-regime micro-cutting of brittle materials without resorting to the tedious trial-and-error methods.