What's the plate glass?
Plate glass, flat glass or sheet glass is a type of glass, initially produced in plane form, commonly used for windows, glass doors, transparent walls, and windscreens. For modern architectural and automotive applications, the flat glass is sometimes bent after production of the plane sheet. Flat glass stands in contrast to container glass (used for bottles, jars, cups) and glass fibre (used for thermal insulation, in fibreglass composites, and for optical communication). Plate glass include general plate glass and float glass.
In the production of plate glass, the glass was slipped across the tin pot. Graphite is used to slide tin to avoid contact with the glass. However, boron nitride can be used in this areas which will take place of graphite.
Float glass can be made in thickness between 1.5 to 20mm. There are two techniques to accomplish this. To produce thin float glass, rollers control the width and speed of the glass ribbon. For thick float glass, the glass floats against graphite barriers, so that the ribbon flows out thicker. Thus the desired widths and thicknesses can be achieved.
While each glass plant is different from the other, the float glass production process can be divided into five universal steps:
1、Batching of raw materials:
The main components, namely, soda lime glass, silica sand (73%), calcium oxide (9%), soda (13%) and magnesium (4%), are weighed and mixed into batches to which recycled glass (cullet) is added. The use of ‘cullet’ reduces the consumption of natural gas. The materials are tested and stored for later mixing under computerised control.
2、Melting of raw materials in the furnace:
The batched raw materials pass from a mixing silo to a five-chambered furnace where they become molten at a temperature of approximately 1500°C.
3、Drawing the molten glass onto the tin bath:
The molten glass is “floated” onto a bath of molten tin at a temperature of about 1000°C. It forms a ribbon with a working width of 3210mm which is normally between 3 and 25mm thick. The glass which is highly viscous and the tin which is very fluid do not mix and the contact surface between these two materials is perfectly flat.
4、Cooling of the molten glass in the annealing lehr:
On leaving the bath of molten tin, the glass – now at a temperature of 600°C – has cooled down sufficiently to pass to an annealing chamber called a lehr. The glass is now hard enough to pass over rollers and is annealed, which modifies the internal stresses enabling it to be cut and worked in a predictable way and ensuring flatness of the glass. As both surfaces are fire finished, they need no grinding or polishing.
5、Quality checks, automatic cutting, and storage:
After cooling, the glass undergoes rigorous quality checks and is washed. It is then cut into sheets of sizes of up to 6000mm x 3210mm which are in turn stacked, stored and ready for transport.
