The use of safety glass is today the standard for car windows. Normal window glass would form dangerously sharp pieces of broken pieces with a high risk of injury in the event of a break. There are different variants of safety glass, which we will introduce below.
Laminated safety glass
This later introduced safety glass is primarily used for windshields. Here lies between two glass layers a film. A clear break of the disc is thus hardly possible. Laminated glass (LSG) is sometimes referred to as composite safety glass or rarely as safety laminated glass.
Tempered safety glass (ESG)
The toughened safety glass was the first correct safety glass for car windows. These are hardened and tempered disks, which break up into many small pieces when broken. The fragments are so small that deep injuries are practically impossible. ESG is mainly used for the rear and side windows. The glass carries a disc stamp with terms like "tempered". For the first time, ESG was used in the 1930 years, the glassworks Herzogenrath filed a patent for 1930 and distributed it under the brand name "Sekurit". Single-pane safety glass withstands the strongest demands, such as hammer blows.
The fracture pattern is characteristically a dense network of fine cracks. In case of breakage, it breaks explosively into glass crumbs, which is why it is nicknamed "Krümelglas". It is heated to 620 ° C in a tempering oven to produce a soft, doughy consistency. Now it can be brought into any desired shape. This is followed by shock cooling with cold air, the glass surface cooling much faster than the glass core. In this way, compressive stress is generated on the surface, while tensile stress is generated in the core. This bias discharges abruptly at a break, which leads to crumbling.
Advantages of tempered safety glass
- increased flexural strength of 120 N / mm², for comparison float glass: 45 N / mm²
- increased shock and impact resistance
increased thermal shock resistance of 200 K, for comparison Foatglas: 40 K - Robustness: ESG is so robust that it can also be easily installed and removed. The laminated glass is more sensitive in this regard.
