Ceramic – Glass
Annealing – After the Glass ribbon is formed in the bath of molten tin, the glass enters the annealing stage which consists of two zones: the permanent and the temporary. The permanent zone is the zone which has a temperature range of 550C to 490C. It is in this zone that the strength, flatness and cutting properties of the glass at room temperature are determined. This is termed as the permanent zone because the above said properties which are obtained in this zone will remain permanently with the glass unless it is re-heated or tempered.
The range below the permanent zone is the temporary zone where the glass is rapidly cooled to bring the temperature below the room temperature. At the room temperature all the temporary properties vanish and only the permanent properties remain with the glass. The cooling rate is an important factor to keep an eye on, as improper cooling rates will result in flatness or cutting problems and may also cause breakage.
To be Contd….
