Why do glass produce pits after tempering treatment?

Tempered glass is actually a type of prestressed glass. To improve the strength of glass, chemical or physical methods are usually used to form compressive stress on the surface of the glass. When the glass is subjected to external forces, it first offsets the surface stress, thereby improving its load-bearing capacity and enhancing its own wind pressure resistance, impact resistance, and other properties.

Glass deep processing enterprises may find that sometimes the original glass may exhibit pitting after being processed in a glass tempering furnace.

Source: Network

The phenomenon of pitting is actually a type of appearance quality defect in tempered glass, and there are several main reasons for the occurrence of pitting:

1. The moisture-proof powder on the glass is stuck to the glass due to moisture or there are impurities on the glass surface, and it is not cleaned thoroughly before tempering;

2. There is insulation material falling off in the upper furnace of the heating furnace;

3. The glass was not cleaned after edge grinding, and after long-term storage, the residual glass powder on it dried and did not clean thoroughly before tempering;

4. The ceramic roller table in the heating furnace was not properly cleaned, resulting in the accumulation of dirt on it;

5. Glass blast furnace, with small glass slag remaining on the roller table.

6. Excessive introduction of sulfur dioxide is due to its strong corrosiveness. Excessive introduction can cause spots on the surface of the corroded roller table, leaving pits on the tempered glass surface. This can be solved by reducing the amount of sulfur dioxide introduced.

The pitting of tempered glass can usually be divided into two types:

One type is dispersed. Individual pockmarks are distributed in a star like pattern, which is caused by the unclean surface of the glass toughening equipment's upper platen or roller table, or the unclean roller table below the air grille. In order to reduce the occurrence of pitting, enterprises should regularly clean the roller table of the glass tempering furnace.

Another type of dense. Usually, the pits are concentrated in an orange peel shape, which is caused by the long heating time of the glass tempering furnace or the high heating temperature of the tempering furnace. This situation can be solved by adjusting the heating time or temperature parameters of the tempering equipment.

Of course, choosing a good tempering furnace equipment is the correct solution.

The heating furnace of Gangxin Steelmaking Furnace is a split steel structure with upper and lower sections. The upper furnace body can be freely lifted and lowered through the furnace top lifting mechanism, with a lifting height of 450mm, making it easy to maintain and clean the furnace. Moreover, the insulation material of the furnace body is made of high-density ceramic fiber board, with the surface brushed with high-temperature resistant adhesive treatment. A layer of magnetized high aluminum plate is laid on the inner side of the furnace to ensure that no impurities fall off, causing product spots and defects.