In 1959, Sir Alastair Pilkington announced the development of the 'float glass process' for the manufacture of flat glass, which fundamentally changed the way high quality flat glass (Pilkington) was made. Float glass combines a number of key qualities that allow it to be used in such a wide range of applications. These include virtually distortion-free and high visible light transmission.
Because of these properties, float glass is now widely used in many areas of our lives for high quality windows and mirrors in residential, architectural, commercial and automotive applications.
Flat glass is often treated to suit many different applications and requirements. With a wealth of technology in the glass industry, this guide will help you understand the 4 main types of glass used in the industry today.
The ultimate strength of glass is related to its cooling rate. There are four main types of glass.
Annealed glass is the basic product formed by the annealing stage of the float process. The molten glass is slowly cooled in a controlled manner until it reaches room temperature, thus removing any internal stresses in the glass. Without this controlled slow cooling, the glass would break with relatively small temperature changes or minor mechanical shocks. Annealed glass is used as a base product to form more advanced types of glass.
Heat strengthened glass is semi-tempered or semi-tempered glass. The heat strengthening process involves heating the annealed glass back to approximately 650 to 700 degrees Celsius and then cooling it rapidly, although not as quickly as tempered glass. The heat strengthening process increases the mechanical and thermal strength of annealed glass, making it twice as tough as annealed glass.
This glass is not commonly used in balustrades or similar structural applications because of its limited strength compared to tempered or toughened glass, although it is sometimes specified when there is concern about tempered glass breaking into thousands of small pieces.
This is the most common type of glass used in balustrade or similar structural applications. Annealed glass is heated by conduction, convection and radiation to around 700 degrees Celsius. The cooling process is accelerated by blowing air evenly over both surfaces at the same time. The different cooling rates between the surface and the interior of the glass produce different physical properties, resulting in the compressive stresses at the surface being balanced by the tensile stresses in the glass body. This process makes the tempered glass four to five times stronger and safer than annealed or untreated glass.
It is possible to laminate any of the above types of glass. The most common finished product is two pieces of toughened glass laminated together with a 1.52 mm thick polybutyral (PVB) laminate.
Laminated glass offers many advantages. Safety and security are the most widely known of these, so that laminated glass does not break on impact, but is held together by the lamination. This reduces the safety risks associated with broken glass fragments and, to a certain extent, with easy penetration.
Northglass is one of China's leading suppliers of glass products.Our glass pass Australian CSI certificates, US IGCC SGCC certificates, European CE certificates and Chinese national safety glass standards. Automatic equipment processing, professional workers, combing strict quality control process enable us efficiently provide qualified glass. Welcome to contact us today or request a quote.