How is Toughened Glass Made

December 13th, 2010 by Ian

Toughened glass, as the name itself suggests, is glass material is tougher than ordinary glass that has low resistance power. These are stronger varieties that are used in various places, whether residential or commercial constructions. In fact, the strength of the toughened glass is up to five times more than that of annealed glasses. Toughened glass is also used to manufacture glassware and these products are comparatively safer and offer more durability. However, the strength of these items should not be confused with any wrong perception of being unbreakable. If products made of toughened glass are handled with proper care, they can last even for a lifetime.

How toughened glass is manufactured

Annealed glass is heated above 720°C, which is the highest annealing point and after the extreme heating procedure, rapid cooling is conducted with air. Taking the surface lower than the annealing point cools off the glass. This causes the surface to become hard and contracts while the core still flows for a while. Finally, the core cools into numerous layers under tensile stress, balanced by compressive surface stresses. Because of these stresses, the toughened glass is strong and tough. However, a scratch on the surface or even a small cheap can weaken the layer and sometimes it may lead to breaking into small pieces.

Alternative process to make toughened glass

There is an alternative process of creating toughened glass, which is done by using certain chemicals. Here the surface layer of the glass needs to be forced at least 0.1mm thick into compression by the exchange of sodium ions in the surface of the glass with the potassium ions that are larger by 30%, by immersing the glass into a molten potassium nitrate mixture. This chemical process of making toughened glass results in more toughness.  This process of manufacturing can be used with complex shaped glass objects.

Different usages of this glass material

Toughened glass items have wide usage. Where the chances of damage and stress are high, this glass variety is used. Typical usages of this glass include counter tops, shelves, glass table tops, doors, window panels, window glazing, etc.. Therefore, it is suitable for use in residential and commercial purposes.

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