Investigation of subsurface damage of ground glass edges

The demand for LCD (liquid crystal display) screens will maintain a rapid growth in the next decade. The high-speed edge-grinding process is important in this industry. One issue is the subsurface damage (SSD) induced by the edge-grinding. Glass is very sensitive to the micro-cracks of the processed surface. To investigate the SSD generated by the edge-grinding process, two grinding wheels with different grit sizes and bonding materials were employed to shape the edges of ultra-thin normal-glass panels and LCD-glass panels with 12 sets of grinding conditions. The cross-sectional microscopy, as a simple and direct assessment method, was utilized to measure the depths of subsurface cracks. It was found that bonding material, diamond concentration, and grit size imposed influences on the material removal mechanism of the edge-grinding process. The edge-grinding conducted using a wheel with grit size = 22-36 mu m, diamond concentration = 100, and bonding material = resin induced little damage to the glass samples. With the smooth edge ground, the majority of the material was removed by plastic deformation. However, the subsurface damage of the LCD glass was smaller than that of the normal glass induced under the same grinding condition, and the LCD showed better machinability. The density of SSD of the LCD glass was also less than that of the normal glass.