By heating the original glass and then suddenly cooling to change the stress distribution and microstructure of the glass, its strength is 4~5 times of ordinary glass, so it is also called tempered glass, it is a kind of safety glass. Because of the broken glass, the debris will break into even small particles and no ordinary glass knife-like sharp angle, which is known as safety glass and widely used in automobiles, interior decoration, as well as open windows outside the high-rise layer.