Laser dressing of vitrified aluminium oxide grinding wheels

Grinding is a manufacturing process that produces engineering components to a desired surface finish. In continuous grinding operations, the grinding efficiency of vitrified grinding wheels deteriorates as the sharp cutting edges become blunt as a result of the formation of wear flats. Dressing is essentially a sharpening operation which addresses this problem by generating a specific topography on the cutting face of the grinding wheel. High power lasers are being explored as a non-contact dressing technique. In the present study, a high power laser was used to produce a resolidified layer on the surface of vitrified aluminium grinding wheels. The high heat flux intensity produced both solid-solid and solid-liquid phase transformations. Microstructural analysis of the dressed wheel surface showed extensive grain refinement. Microcutting edges are produced on the individual grinding grains. Though a wide grain size distribution was observed, grain shape was more regular (equiaxed), with well defined vertices and edges oil each grain. The vertices and edges provide cutting edges for improved grinding at the microscale. Area analysis of surfaces using energy dispersive area analysis (EDAX) revealed the presence of Al, Cr, O, Si, K, and Na. However, X-ray diffractometry on the surface indicated the presence of Al2O3 phase only. The upper resolidified layer contained Si, Na, K, and P, whereas the material below was primarily Al, Cr, and O. This suggests that a glassy phase (with Al, O, Na, K, P, and Si) is formed on the surface. Subsequent laser treatment modified the morphological structure of the vitrified grinding wheel surface, thus creating a dressing effect with locally sculpted microscale cutting edges on each grinding grain. The experimental results indicate that laser modified grinding wheels are comparable in performance to diamond dressed grinding wheels.