What causes surface defects on tempered glass?

1. Roll marks:

Due to the large distance between the roller tracks in the tempering furnace, there is a high jumping force, which may leave roller marks. This can be solved by introducing sulfur dioxide appropriately, as sulfur dioxide can react with the roller surface to form a protective film, reducing the possibility of roller marks.

2. Spicy point:

There are several reasons for the occurrence of pockmarks, such as excessive introduction of sulfur dioxide, which has strong corrosiveness and can corrode the surface of the roller conveyor, leaving spots and pockmarks on the tempered glass surface. Additionally, the roller conveyor itself is not clean enough, with dirt sticking to it. This can also be solved by introducing a small amount of sulfur dioxide, but if there is a lot of dirt, the roller conveyor should be shut down for cleaning.

3. White mist:

Generally, white mist is produced due to insufficient tempering temperature.

4. Tempered Rainbow:

Nowadays, float glass is usually produced. In the production process of float glass, the glass paste is spread flat on the surface of the tin bath under the action of gravity and self tension. There must be one side in contact with the tin surface, and a small amount of tin infiltration will occur. At that time, tin oxide will be produced under the temperature conditions. During the tempering process, tin oxide will be oxidized again under high temperature to form tin oxide, and the volume will expand, causing some micro cracks on the surface of the glass. These cracks will interfere with light when observing the glass under special conditions and angles, resulting in a steel rainbow. The solution is very simple: sprinkle fine polishing powder on the surface of the glass.

5. Wind spots:

This is formed during the cooling process due to uneven cooling, resulting in uneven stress on the glass. When observed from a certain special angle, the glass surface appears as alternating light and dark stripes. Solution: Generally, using air knife cooling instead of traditional air hole cooling can minimize the generation of wind spots.

6. Stress spot:

Stress spots are similar to wind spots and are also caused by uneven stress. For example, during the heating process, there is a temperature difference between the edge and middle of the furnace, which leads to uneven stress. There is currently no way to avoid stress spots in the world, mainly by paying attention to natural factors such as orientation and local climate during installation to make them difficult to distinguish with the naked eye. It is recommended to use a double chamber tempering furnace instead of a traditional single chamber tempering furnace to minimize stress unevenness.