Papers by Author: Jian Yun Shen

Abstract: In the present research work, a new precision sawing technique is proposed, by which the ceramic workpiece is ultrasonically vibrated along the blade radial direction during the sawing operation using a diamond blade. In this study, experiments are conducted to study the sawing force characters of ultrasonic vibration-assisted sawing (UVAS) and conventional sawing (CS). The influences of the sawing parameters on the sawing force and force ratio are investigated. The results show that the sawing force in UVAS is smaller than those in CS. It was found that applying ultrasonic vibration to the sawing operation decreased the normal sawing force 18%-38% and tangential sawing force by 10%-25%. The force ratio in UVAS is lower than that in CS, which reveals that diamonds are easier to cut into the ceramic workpiece and the material machinability is improved.

Abstract: The path distribution can directly affect the machined workpiece surface quality in lapping and polishing, such as planeness, roughness, etc. In present paper, the influence of rotate speed ratio (RSR) and abrasive position on path distribution was analyzed with a single fixed abrasive. The results show that the RSR and abrasive position has heavy influence on the path distribution. The path distribution with decimal RSR is more intensive and complicate than that with integer RSR, especially complex decimal RSR, and it can be also affected by the abrasive radial and circumferential position, but the shape of path is not changed with different abrasive circumferential position which only affects the initial phase angle of path.

Abstract: The surface roughness and surface morphology of silicon wafers polished by three different polishing methods were analyzed in this paper. A polishing pad was prepared by means of sol-gel technology as semi-fixed abrasive tool. An electroplated polishing pad was chosen as fixed abrasive tool. And a polishing cloth was chosen as free abrasive tool. The results showed that the surface of silicon wafer polished by the sol-gel polishing pad was superior to the other two. It was easy to get mirror effect with few scratches while the free abrasive and fixed abrasive got lots of scratches on 23silicon wafers. The surface roughness of silicon wafer polished by the sol-gel polishing pad reached 1.41nm measured by atomic force microscope (AFM).

Abstract: Based on the analysis of problems of diamond cut-off wheels used in slot grinding of ceramics at present, a brazed diamond cut-off wheel was produced and analyzed. Two typical advanced ceramics, alumina and silicon nitride, were used as the workpiece materials. In the experiments of slot grinding of ceramics, grinding ratio, wear process of the wheel and grinding quality of the work were studied. Experimental results showed that the brazed diamond cut-off wheel obtained good grinding ratio and abrasive resistance. The surface roughness of ground silicon nitride was better than that of alumina.