Float glass is a flat glass produced using the float process, in which the molten glass is directed to a tin bath. The lighter glass floats on the tin and spreads evenly. Flat, flat letters with plan-parallel surfaces can be produced.
About 95% of all flat glass is produced today using the float glass process.
Raw materials for the production of float glass are:
- Quartz sand
- Calcium carbonate (lime)
- Dolomite
- Sodium carbonate
- Residual glass cullet
The sodium carbonate reduces the melting point, the calcium carbonate affects the hardness of the glass.
Production
A float glass plant is between 300 and 800 m long. In it, the molten glass, consisting of the above-mentioned raw materials, is placed on a liquid tin bath at a temperature of approx. 1100°C. This process takes place endlessly and continuously for about 11-15 years.
The liquid, lighter glass floats on the tin bath and spreads very evenly until it has reached the so-called equilibrium thickness. The balance thickness is usually about 7mm. However, the glass thickness can be regulated by the speed of rolling in the cooling area. The higher the speed of rolling, the thinner the glass. Glass thicknesses from 2 to 19mm can be produced.
Stages of the production process:
- I: At approx. 1100°C, propagation of the glass mass on the tin bath
- II: cooling of the glass to approx. 700°C, capture of the glass strip by rollers
- III: heating of the glass to approx. 850°C, Stretching to the required glass thickness by rolling speed
- IV: Cooling to approx. 650°C
- V: Lifting of the glass strip from the tin bath by rolling
glasses can be manufactured in dimensions of up to 18 m long and approx. 3.60 m wide. This large format allows a lot of freedom in the design of glass façades, for example.
Float glass can be used in many areas: shop windows, furniture, conventional windows and mirrors.
Features:
- Virtually free of bubbles, inclusions and streaks
- High light transmission
- High thermal shock resistance
- Good water and alkali resistance
- Weight: approx. 2.5kg/m² and mm glass thickness
- Ug value of 5.8 W/m²K for 4mm float glass
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