Tempered glass is heated to 650℃softening point, glass this time still can keep the original shape, but the glass particles can migrate, its internal structure adjustment, the presence of stress quickly eliminated, then the glass for cooling, when the temperature of cooling, the glass surface pressure, internally generated tension, glass produced a uniform and the stress distribution, improve the glass as the tensile strength of brittle materials, once the glass broken is a small particles, no serious harm to people, no sharp corners, with a certain degree of security. Therefore, toughened glass is safety glass.