In daily life, we often come into contact with tempered glass products, such as coffee tables, tempered glass doors, tempered bathroom doors, and so on. When cleaning such items, we may find that some tempered glass cannot be washed clean. What is the reason why the glass cannot be washed clean? The reason why tempered glass cannot be washed clean is because the quality of the glass does not meet the standards, and defects such as glass ribs and pits appear after tempering. The following is a list of points:
Whether the quality of tempered glass meets the standards or not is determined by the rationality of process parameter settings in the forced convection furnace, in addition to the reasons for glass raw materials. Only by thoroughly understanding their roles and interrelationships can high-quality tempered glass be produced. All parameters are designed around "uniform heating and rapid cooling", but they are not isolated, they are an organic whole, and must be comprehensively considered to obtain a perfect process. Temperature related glass defects and correction methods:
1. Wave tendon
If the set temperature is too high and the heating time is too long, the glass will experience waves. This is because the heating of the glass has exceeded the critical point and the glass has started to soften. If this defect occurs, it can be solved by shortening the heating time.
2. Pitted spot
Long heating time can also cause pits on the lower surface of the glass, which can be divided into two types. One type is dense and orange peel like, which is caused by long heating time. (Especially for thick glass with a thickness of 12 millimeters or more, some units set the heating time too long to prevent it from breaking, and adjustments can be made according to the situation.). Another type is individual star shaped pits, which are caused by the unclean surface of the loading table and ceramic rollers, or the glass fragments of the air grille roller track not being cleaned up.
3. White mist
White fog is a white mark that appears in the middle of the lower surface of the glass, usually in the first few heats of initial production. This is caused by the high surface temperature of the ceramic roller. When the glass enters the furnace for several tens of seconds, the lower surface of the glass is directly subjected to heat conduction and the four corners curl. The contact surface between the glass and the ceramic roller decreases, and the friction with the ceramic roller increases, causing it to disappear as the surface temperature of the ceramic roller decreases. We can set the lower temperature and power of the lower part to be lower during initial production. In addition, we must continue production and not let the furnace idle. If we do not produce temporarily, we can turn off the heating switch to prevent white fog.
4. Bending
When we produce tempered glass, if there is bending, it is usually solved by adjusting the wind pressure or adjusting the blowing distance, which is very effective and fast. But some operators do not understand that the difference in temperature between the upper and lower parts can also cause bending of the glass. Assuming that the blowing distance and wind pressure of the air grid section are equal, if the four corners of the glass bend upwards, it indicates that the lower temperature is too low. On the contrary, if the four corners of the glass bend downwards, it indicates that the lower temperature is too high. If it is necessary to adjust the temperature to make the glass flat, it cannot be solved by one or two heats, and it will take several heats before it can be done.
5. Sphere
This occurs when making thin glass with a thickness of 6mm or less and the layout is relatively large. The temperature adjustment function can be used to increase the temperature of the upper and lower longitudinal directions in the middle, sometimes requiring an increase of about 30 degrees. (Increments from the second row on both vertical sides to the middle). An excellent operator should understand that the relationship between temperature and optical performance is: high temperature and long heating time lead to high yield, but poor optical performance; On the contrary, if the temperature is low or the heating time is short, the optical performance is good, but the yield will be low. This requires us to carefully summarize and find the best effect. The temperature is closely related to the particle size of tempered glass; Under the condition of equal wind pressure, particles with high temperature are smaller, while particles with low temperature are larger.
