Temperrd or Heat-Resistant glasses

Temperrd or Heat-Resistant glasses
Temperrd glasses are prouduced by applying thermal process on regular glass.Initially, glass must be prepared and cut in considered dimensions and form, because strsses applied on the glass due to tempering process may make impossible conducting any work such as cutting, boring and sand blasting and it may cause glass breakage.
After cutting the glass in required forms and sizes, its four edges will be turned by diamond machine.Then glass is heated in a specific oven to the temperature of 625 C.Then it taken out of the oven and put on cooling department. In this part, glass is quickly cooled under a controlled process.( for producing semi-temperrd glasses, the cooling process is done slowly). Quick cooling the glass causes compressive stress in its surface and tensile stress in its middle parts.The basis is such that external parts of glass are cooled quicker than internal parts and are contracted,however, its internal parts that are yet hot and relatively fluent don’t prevent contraction.Consequently, there is no stress in the glass.However, in lower temperatures when central parts are beginning to cool, the surface parts that have become solid prevent contraction of central  layers.Consequently, it makes tensile stress in the central parts and compressive stress in the surface of the glass.
Glasses that have been temperrd by this method, if  franctured,will be turned into a large number of fine particles lacking any cutting edges having lower risk for user.The more number  of particles from fracture and lower size of its dimensions means higher security of the glass. Therefoer, thenumber and dimensions of particles from fracture is considered as a measure for evaluating the quality of these glasses in related standards.
Tempered glass is more resistant against mechanical loads, thermal stresses , wind, weight of the snow and impact up to 4 to 5 times than regular glass with the same dimensions and thickness.
In the process of securing  the glasses,their color,chemical component, percentage of lihgt pass, physical properties for energy and sound ,specific  weight,melting point,thermal conduction and expansion coefficient remains unchanged with mechanical strength is the only property changed,i.e.increased.
Which glasses must  be tempered or secured?
Tempered glasses are used when building standards recommend using security glasses (full- glass facades). It is also recommended to use colored glasses,reflex and particularly low-E as security or tempered glasses due to higher thermal absorption. It is also recommended to use tempered glasses in the vitrine of shops, fixed and mobile entrance gates, windows of windy areas, commercial buildings and partitions.