What Is The Reason for The Appearance of White Mark Spot Mist After Tempered Glass Is Tempered? And The Solution To This Problem

During the production of tempered glass in a glass tempering furnace, it is inevitable that various reasons may lead to poor performance in the production of tempered glass, such as edge cracking, pitting, and white mist. We have previously discussed how to avoid the occurrence of pitting and edge cracking in the processing of tempered glass. However, the reasons for white mist occurring in different positions of the glass may vary. Therefore, we will analyze and explain what causes white mist in tempered glass in a glass tempering furnace.

1. White mist appears in the middle of the glass

1.1. Reason for the problem

The appearance of white mist in the middle position of the glass may be due to the fact that the glass tempering furnace has not been used for a long time. When production is just resumed, the ceramic roller conducts heating, and the upper part is subjected to radiation heating and forced convection heating. The overheated ceramic roller causes the lower temperature of the glass to be higher than the upper temperature. Due to the thermal expansion of the lower surface of the glass, the surrounding areas curl upwards, and the weight of the glass is several times in the middle of the glass, causing repeated friction between the middle position of the glass and the ceramic roller to produce white mist.

1.2. Solution

As the running time of the glass tempering furnace gradually accumulates, the glass will take away the heat on the roller path, reduce the temperature difference between the top and bottom of the glass, and reduce the degree of white fog on the glass. Generally, it can be improved and solved by increasing the upper jet and temperature or lowering the lower temperature.

2. White mist appears on all sides of the glass

2.1. Reason for the problem

The appearance of white mist on all four sides of the glass may be due to the fact that the upper temperature of the glass is higher than the lower temperature when it enters the tempering furnace, causing the four sides of the glass to curl downwards, concentrating the weight of the glass on the edges, and causing friction with the ceramic roller. The originally small-sized glass was damaged after long-term friction with the roller, causing the contact position between the glass and the ceramic roller to be lower than the height of the original ceramic roller. Replacing the large-sized glass original sheet resulted in the uneven level of the ceramic roller.

2.2. Solution

Increase the temperature at the lower part of the tempering furnace or decrease the temperature at the upper part of the tempering furnace to prevent glass warping caused by temperature differences. At the same time, sulfur powder can be sprinkled on the glass, which is not ordinary sulfur but sublimated sulfur. When burned at high temperatures, it gasifies without leaving any residue, which can prevent the glass from sintering with the tempering furnace roller and protect the roller. Note that the surface of the glass will turn blue after sulfur is sprinkled, and it will become transparent after cleaning with a cleaning machine.

3. White mist appears on the entire glass surface

3.1. Reason for the problem

The appearance of white mist on the entire glass surface may be due to inconsistent operating speeds or horizontal differences between adjacent ceramic rollers. Ceramic rollers may break, roller bearings may be damaged, transmission belts may be too loose or broken; ceramic rollers may deform or have inconsistent installation heights; and the number of rollers driven by adjacent motors may be inconsistent, resulting in inconsistent operating speeds of rollers.

3.2. Solution

The operating speed of the roller track can be adjusted by replacing the ceramic roller track, replacing the roller track bearings, reinstalling the transmission belt, adjusting the roller track height, and changing the number of ceramic rollers driven by the motor to maintain consistent and horizontal operation.

4. Intermittent irregular white mist

4.1. Reason for the problem

Observing the irregular intermittent white mist on the glass, it is often caused by uneven temperature during the contact process between the glass and the thread, resulting in local deformation of the glass and friction with the ceramic roller. In this case, other temperature adjustments cannot solve the problem.

4.2. Solution

At this time, the phenomenon can be eliminated by replacing the threaded ceramic roller with a regular ceramic roller. At the same time, tempered glass with production problems can be reduced or solved by adding sublimation sulfur fumigation furnace. This principle is to form a sodium sulfate film on the surface of the roller to protect and lubricate the roller, reduce the adhesion of small glass debris on the roller, affect the quality of the glass product, and extend the service life of the roller.