The art of manufacturing glass is an old one. It was a process which has been refined for thousands of years. With technology becoming increasingly advanced, glass manufacturers have begun producing float glass that is much sturdier, durable and compatible with glass processing procedures of lamination, tempering, acid etching, sand blasting, etc.
At Asahi India Glass Ltd., the highest quality glass manufacturing techniques are used to produce the perfect sheets of float glass. The technique used is the PPG process which was discovered by Sir Alistair Pilkington in the year 1952, and is still the most trusted float glass manufacturing process. Naturally, it has a lot of steps involved in it, and at each individual stage, great care is taken to be precise and thorough with the production of glass.
From selecting the right type and ratios of ingredients for glass to assimilating them all scientifically to produce glass as we know it, here we answer the question of how is glass made through a step-by-step process:
1. Melting and Refining
In order to make clear glass, the right set of raw materials is required. This consists of silica sand (SiO2), sodium oxide (Na2O) from soda ash, calcium oxide (CaO) from limestone/dolomite, dolomite (MgO), and feldspar (Al2O3). These ingredients are mixed in the right proportion, and the entire batch is flown into a furnace heated to 1500 degree Celsius.
In order to impart colour to the glass, certain metal oxides are also mixed in the batch.
2. Float bath
The molten material from the furnace flows into the float bath which consists of a mirror-like surface made from molten tin. This material enters the bath at 1500 degree Celsius and leaves the bath at around 650 degree Celsius. Its shape at the exit is like a solid ribbon.
3. Coating for reflective glass
Thereafter, if one is producing reflective glass surfaces that help in keeping indoors cooler, then coating procedures are followed in which either a hard coat or a soft coat is applied on the surface of the cooled ribbon at high temperatures.
Next, in order to remove the internal stresses built up in glass, a process called annealing is done. This process allows the glass ribbon to pass through a layer which eliminates any stresses on the glass surface and gradually cools it to give it its final hardened form. This makes it easier to cut the glass and shape it accordingly.
Through acute and advanced inspection technology, more than a 100 million inspections can be made throughout the glass manufacturing procedure to identify air bubbles, stresses or grains of sand that refuse to melt. This is essential in quality-proofing the final form of glass.
6. Cutting to order
Finally, diamond steels are used to trim and cut the glass ribbons into square shapes.