For the glass of car windows various types of safety glass are used. Probably the most used is a variant of the ESG (toughened safety glass) is: toughened safety glass (ESG) is thermally toughened glass: the production is a float glass cut to the desired level, provided with additional holes etc and ground at the edges. Then the glass is heated to about 600 degrees and then quickly cooled to room temperature. The rapid cooling causes solidify the outer zones of the discs faster. The cooling at the same time leads to the fact that the inside of the glass contracts, which is hindered by the already solid outside. This creates a desired stress distribution in the glass: the outer surface of the disc is under pressure voltage – the core of the disc under tension.
The tensions are in the intact disc to each other in balance. This has the ESG a high resistance to mechanical and thermal loads. In an accident demonstrates the advantage of the glass because when broken the glass, however, the tension dissolves and the glass shatters instantly into a multitude of small, dull crumb – which means a significantly lower risk of injury than accidents with normal glass. To the side is used almost exclusively single-pane safety glass. The only exceptions are some special vehicles, such as in security or personal protection, there are also special plastic or glass combinations used. The reason for this is a disadvantage of ESG – the glass offers less protection against intrusion, since it can easily be destroyed with a hard object. a toughened glass a little more damage, has not led to the split Hat, for example stone, should rapidly an auto glass replacement carried out, since otherwise there is a risk that the stress distribution is so disturbed that the glass at low levels of mechanical stress cracks.