Hot-wire thermal stress cleaving process of glass with micro crack-free edges

Micro cracks can form on the edges of ultra-thin glass sheets during the cutting processes that use a laser beam or a diamond scriber. These micro cracks can extend to the surface, and thus, it is difficult to prevent ultra-thin glass sheets cut using these existing processes from fracturing under either external stress or acceleration. A thermal stress cleaving process that uses a heated electric resistance wire to avoid micro cracks during the cutting process was proposed. The glass sheets are cleaved following a defined profile because of the thermal stress. In this study, a hot-wire thermal stress cleaving model was investigated based on the principle of thermal stress fracture. The thermal stress in the material was calculated. Experimental studies are performed to investigate the processing parameters, and glass sheet with thickness of 300 mu m was cut, resulting in micro crack-free edges with a surface roughness of 0.5 nm. The proposed process was also applied to cut X-ray telescope lenses substrates with no micro cracks. Compared with diamond scribing and laser cutting, the proposed method is lower capital costs and yields a nondestructive cut surface for glass. The technique can be applied in manufacturing glass products (i.e. lenses, solar cells, glass screen).