Main Types of Glass and Alternative Materials used in Automotive.
Today, flat (float) glass comes in many highly specialised forms intended for different products and applications. Flat glass produced by way of the float process is often further processed to give it certain qualities or specificities. In this way, the industry can meet the various requirements and needs of the automotive and subspecialties like solar absorption or reflectance.
Annealed glass is the basic flat glass product that is the first result of the float process. It is common glass that tends to break into large, jagged shards. It is used in some end products and often in double-glazed windows. It is also the starting material used to produce more advanced products through further processing such as laminating, toughening, coating, etc.
Toughened glass is treated to be far more resistant to breakage than simple annealed glass and to break in a more predictable way when it does break, thus providing a major safety advantage in almost all of its applications.
Toughened glass is made from annealed glass treated with a thermal tempering process. A sheet of annealed glass is heated to above its "annealing point" of 600°C; its surfaces are then rapidly cooled while the inner portion of the glass remains hotter. The different cooling rates between the surface and the inside of the glass produces different physical properties, resulting in compressive stresses in the surface balanced by tensile stresses in the body of the glass.