Papers by Author: Juan Yu

Abstract: Based on the magnetorheological (MR) effect of abrasive slurry, the particle-dispersed MR fluid is used as a special instantaneous bond to cohere abrasive particles and magnetic particles so as to form a dynamic, flexible tiny-grinding wheel to polish optical glass, ceramic and other brittle materials of millimeter or sub-millimeter scale with a high efficiency. Experiments were conducted to reveal the effects of different process parameters, such as grain sizes of abrasive particles, machining time, machining gap between the workpiece and the rotation tool, and rotation speed of the tool, on material removal rate of glass surface. The results indicate the following conclusions: material removal rate increases when the grain size of abrasives is similar to that of magnetic particles; machining time is directly proportional to material removal, but inversely proportional to material removal rate; machining gap is inversely proportional to material removal; polishing speed has both positive and negative influence on material removal rate, and greater material removal rate can be obtained at a certain rotation speed. In addition, the difference of the machining characteristics between this new method and the traditional fixed-abrasive machining method is analyzed.

Abstract: In this study, Fe3O4 particles were used as magnetic particles to form Fe3O4 magnetorheological (MR) fluid, and experiments were conducted to polish optical glass using this Fe3O4 MR fluid. The machining characteristics of glass surface with different MR fluids that are added diamond abrasives and short fibres are studied. Experimental results indicate that the tiny-grinding wheel based on the Fe3O4 MR fluid can effectively polish optical glass and that the maximum diameter and depth of machined region increase obviously in the presence of diamond abrasives and short fibres. When both of diamond particles and short fibres are added to the Fe3O4 MR fluid, the removal efficiency of the tiny-grinding wheel is markedly enhanced due to the synergetic effect of diamond abrasives and fibres.

Abstract: Based on the magnetorheological (MR) effect of abrasive slurry, this paper presents an innovative superfine machining method. In this technique, the particle-dispersed MR fluid is used as a special instantaneous bond to cohere abrasive particles and magnetic particles so as to form a dynamical tiny-grinding wheel. This tiny-grinding wheel can be used to polish the surface of brittle materials in millimeter or sub-millimeter scale. The characteristics of the machined glass surfaces examined by the scanning electron microscope (SEM) and the Talysurf roughness tester confirmed the effectiveness of the finishing technique. The machined surface with convex center and concave fringe demonstrates that the material removal process is dominated by the synergy of the applied pressure and the relative velocity between the abrasives and workpiece. In the case of glass finishing, the mode of material removal is found to be plastic, and controlled by the abrasive-wear mechanism.