Solid Tempered Glass Manufacturer,Solid Glass Exporter,Tempered Glass Exporter,Solid Glass Supplier

Manufacturing Process
Toughened glass is made from annealed glass via a thermal tempering process. The toughening process is made up of three stages: the first consists in rapid, forced and uniform heating up to a temperature of 650-680°C on the entire sheet, and then the successive stage uses a fan to blow air for rapid, forced cooling. This is the key operation in the process and it is this process that creates the surface tension on the sheet for increased mechanical resistance.

In terms of physics, the glass sheet at the toughening temperature loses its characteristics of rigidity and non-deformability; it becomes soft, deformable like a sheet of gelatine. During the rapid cooling stage of toughening, the outer layer of the two largest faces of the sheet cool faster than the centre creating strong compression stress between the two cooler, outer layers and the hotter inner ones. This rapid forced cooling, which takes between 3 and 10 seconds in relation to the thickness, "imprisons" the forces in the sheet, which in the meantime has returned to its rigid and non-deformable state. The next stage entails controlled cooling to return the glass to a temperature where the finished product can be handled.

The improved strength of toughened glass is a result of the stress profile that is induced in the glass by the toughening heat treatment process. Due to tempering process, the glass surface is in compression, while the centre is in tension. This stress profile in the glass is successful as most failures start at the surface from tensile loads. In toughened glass, the applied tensile load must overcome the compressive stress at the surface before the surface can go into tension and fail.

Specification:

Maximum Size : 2440mm x 3660mm
Minimum Size : 300mm x 300mm Glass
Thickness: 3.5mm - 19mm
Glass Types: Clear, Tinted, Reflective, Low e, Figured

Precautions

Once toughened, the glass cannot be cut, drilled, bevel, deep etched or given any kind of acid treatment.
Strain pattern is not a defect, this is a common characteristic of all tempered glass. This is visible when toughened glass is viewed at sharp angles or under certain lighting conditions.
Spontaneous breakage is a result of impact damage, internal inclusions, wild splatter or windblown debris. Where this breakage is a concern, heat strengthened/ heat soaked glass should be considered.
As toughened is heat treated, bow , wrap or process roll distortion may be evident. This is within limits set by ASTM standard.

Tempered Glass Properties
Tempered glass is manufactured by annealed glass through thermal tempering process. During the process, glass is heated to slightly lower than its softening point (usually 630°-650°) and then cooled rapidly to the room temperature.

Usually, tempered glass is used in front exterior of a building, glass cookware, construction of frameless doors, structurally loaded applications, etc. It is also used in those areas where there is a risk of human impact or thermal breakage.

Some of the properties of these tempered glasses are:

It is approximately 4 to 5 times stronger than normal glass of same thickness and size.
Tempered glass brakes into small pieces after breakage, reducing the risk of any type of injuries.
A fully tempered glass has high edge strength, which makes its ideal for glazing applications.
It has significantly higher thermal strength than annealed glass, which ensure no thermal breakage.

Quality of Tempered Glass

Though the process of glass tempering is simple, yet it requires perfect level of accuracy in order to ensure requisite quality standards. Slight difference in process control may leads to various quality disorientation. Some of the quality parameters, which are crucial for the tempered glass, are:

Optical disorientation
Optical disorientation is defined as the blurred images produced by transparent or glazed tempered glass. Usually, it is caused by the minor waves on the glass surface created by furnace and its rollers. Effective manufacturing techniques significantly reduce the occurrence of optical disorientation up to a larger extent. Safex solid tempered conforms to ASTM standard C 1048.

Roller Marks
Roller marks are prominently apparent small white marks on the tempered glass surface along with the line of glass movement. Roller marks occur due to the improper maintenance of rollers and furnace chamber. It can also be caused by infrequent cleaning of furnace and negligible preventive maintenance.

Waviness and Bending
The process of extensive heating and then rapid cooling imparts certain amount of distortion and curve along with glass surface. It happens due to the compressive and tensile stress developed in glass during this process. This results distorted images under certain viewing conditions. Though it is not considered as a major defect for a heat-treated glass, it can be avoided by proper maintenance and good insulation.

Edge Strength
The edge strength of heat-treated glass is significantly higher than that of annealed glass. Edge strength is an important factor in determining the property of thermal resistance for a glass. It also makes tempered glass suitable for various glazing applications. Uneven heating and poor grinding lead to low edge strength. Quality procedures and effective grinding determine the excellent edge strength.

Fragmentation
After the breakage of tempered glass, the fragmentation pattern reveals significant characteristic of the tempered glass. If the fragmentation is even and contains small pieces of consistent sizes then the quality of the tempered glass is up to the mark. Large pieces show weaker strength of glass. Fragmentation also revels the quality of heating control.

Coating burns
Coating Burns in Reflective Glasses and Low- E glasses, take place due to the presence of high temperature pockets inside the furnaces. These pockets inside the furnace result into coating burns in some areas, which cause damage to the coating. The coating-burns can be avoided by using CNC machines for scoring and cutting of the coated glass.

Spontaneous Breakage
(Nickel-sulphide inclusion)
Sometimes, tempered glass breaks without any apparent reason because of the presence of microscopic nickel-sulfide (NiS) stones. In annealed glass, the NiS materials are in stable state, which get excited after heating. When the glass is subjected to rapid cool, these NiS particles remain in their excited state. Later on, these particles expand under certain environmental factors that cause the breakage of tempered glass. Though this problem is severe, yet it happens in rare case.