Material removal mechanism in rotary in-feed grinding - Modeling and analysis -

The rotary in-feed grinding is the most promising process to ensure the controllability of wafer geometry including the thickness and flatness. This makes it be widely applied into manufacturing of mono-crystal wafers, such as silicon, silicon carbide, sapphire, lithium tantalate, and etc. Unlike the conventional surface grinding, however, the rotary in-feed grinding is a complex material removal operation in which the extent of interaction between the abrasives and wafer keeps varying during the wheel/wafer contact zone. Such characteristic property significantly influences the chip formation, the homogeneousness of surface topography, the variations in grinding forces and the power consumption in the radial direction of the wafer. In this paper, the grinding mechanisms including the geometry, statics and surface topography were theoretically analyzed on a proposed grinding model and organized as follows. Described in Section 2 is the geometric analysis which mathematically expresses the wafer profile and a variety of information regarding to the dimensions of chip formed. The results suggest that the chip cross section increases proportionally as increasing in the wafer radial distance. Based on the results of chip formation, the grinding forces respectively exerted on an individual abrasive, a single wheel segment and whole wafer are calculated in the Section 3. Also, the necessary grinding power and generated grinding heat are estimated by statics analysis. In the Section 4, the surface roughness and its variation in a radial direction of the wafer are then derived by taking into consideration of the distribution of abrasive protrusion in height-wise.