What Is Float Glass?
Float glass is a type of flat glass produced by floating molten raw material in the molten tin method. It gives it an excellent sheet flatness and uniform glass thickness. 90% of glass in today’s world is from the floating process.
How It’s Made?
Step 1: Batch Mixing
It begins with the earth’s abundant raw materials: sand. Glass itself is also an ingredient. Its recycling reduces the need for raw materials and accelerates the melting process. Next, the silica sand, soda ash, limestone, and other raw materials mix in proportion and sending into a furnace. The raw material will be heated at about 1500℃ in the furnace to become liquid and merges. Then, it’s ready to leave the melting furnace and enter a bath of molten tin.
Step 2: Molten Tin Float Bath
The glass comes out from the furnace, flows gently and spreads out, looks like honey, and becomes a flat continuous ribbon in the tin bath. As we know, tin is a low melting point metal; its molten liquid level is flat and smooth. As a result, it makes glass a good flatness and no water ripples. In addition, there’re top rolls to act on the spread surface of the glass, control the glass speed and thickness.
Step 3: Annealing Lehr
At the end of the float bath, the glass is cooled down further and leaves the tin bath at 600℃, when it is just solid enough to climb on metallic rollers and be driven inside the lehr. In the lehr area, the glass is annealed and gradually cooled to relieve inner stresses and prevents splitting in the cutting phase: cool down too quickly, it would break.
Step 4: Inspection& Cutting
After the cooling, high-performance scanners detect all kinds of defects and identify imperfections to be discarded. When the glass passes the quality inspection, it will be cut into desired dimensions and packed depends on specific customer requirements.
How Many Types Of It?
There’re two main types: clear or tinted. There is clear and ultra-clear float glass in the clear category. And grey, bronze, green, blue, etc., in the tinted category. Click each following to see the specification details:
Clear Float Glass
It has a flat and smooth surface. Without ripples, it is a good vision, good transparency, and strong daylighting.
Ultra Clear Float Glass
It is low-iron float glass. It has an excellent light transmittance, with an attractive appearance and high optical qualities.
Tinted Float Glass
This is a color glass with heat-absorbing. By adding different metal oxides, the float glass will have different colors. The primary colors are grey, bronze, green, and blue. Despite adding beautiful colors to the building appearance, it has the primary function of low UV transmittance, reduces solar heat gaining and glaring.
Float Glass Applications
Most safety and decorative glass, such as laminated glass and toughened glass, is further process by standard float glass. In the building industry, it makes curtain walls, doors, and windows, partitions, etc. While in the automobile industry, it makes windshields, windows, etc. Moreover, it makes mirrors, tables, shelves, display cabinets, and many other consumer products. It is the most widespread form of glass in today’s world.