What Is The Problem of Tempered Glass Always Breaking in The Production of Tempered Glass in A Glass Tempering Furnace? How To Solve It?

Tempered glass is cut into the required dimensions after production and enters the glass tempering furnace to complete tempering. The common problem with glass during the tempering process is cracking, which mainly occurs in the heating stage, quenching and cooling stage, and tempering stage of the glass. The reasons for glass breakage are also different in different stages. Below, the glass tempering furnace manufacturer will introduce to you what problem tempered glass always breaks? How to solve it.

1. Glass breaks in the heating section

1.1. Cause of fragmentation

1.1.1.Quality defects such as stones and small bubbles appear in glass. Glass belongs to brittle materials, and its mechanical behavior follows fracture mechanics. When stones or small bubbles appear in glass, cracks will form inside the glass. In the tensile stress zone of tempered glass, it will shatter during heating.

1.1.2. The glass substrate itself has quality issues such as small cracks. During glass production, transportation, processing, and storage, it is easy to cause scratches and edge collapse. A large number of micro cracks will appear on the surface. Under certain conditions, such as the effect of heated water vapor, the cracks will rapidly expand and cause fragmentation.

1.1.3. The thermal shock performance of glass weakens, and the thickness of glass affects its thermal shock performance. The thicker the glass, the weaker the thermal shock performance, so when adjusting the heating temperature and duration, we also need to consider the thickness of the glass.

1.1.4. The uneven temperature inside the heating furnace caused mechanical fracture and warping deformation.

1.1.5 The glass original has already undergone tempering or semi tempering treatment, and it is also prone to cracking during the heating stage.

1.2. Solution

1.2.1. Carefully inspect the glass raw material before entering the furnace, and supplement the light source appropriately for testing.

1.2.2. Only qualified float glass can be obtained for testing and experimentation.

1.2.3. Detail treatment and quality control should be carried out on the edges and edges, and glass raw materials without edge treatment cannot be tempered.

1.2.4. Adjust the temperature and convection size of the heating section of the tempering furnace to avoid large temperature differences between the surface and interior of the glass, which may cause glass breakage and deformation in the furnace.

1.2.5. Tempered glass or semi tempered glass circuit operations have a high risk of breakage, and the return glass itself has quality issues, so glass return to the furnace should be avoided.

1.2.6. The temperature setting should not be too high, and the convection setting should also be reduced accordingly. Generally, the thicker the glass, the larger the layout, and the heating speed should be slowed down.

2. Glass breaks during cooling and tempering

2.1. Cause of fragmentation

2.1.1. Glass breaks within one minute of quenching and tempering, possibly due to the glass itself not reaching the tempering temperature.

2.1.2. The temperature difference between the top and bottom of the glass is significant, and the mechanical properties of the glass are broken due to deformation.

2.1.3. Partial air outlets are obstructed, resulting in uneven tensile stress in various areas of the glass and glass breakage.

2.1.4. From the heating furnace to the quenching chamber, the overall or local temperature of glass decreases, and the surface compressive stress is low during air cooling, resulting in a large temperature difference between the inside and surface of the glass

2.1.5. Poor quality of the glass raw material, or non-standard requirements or quality defects at the opening, can also cause the glass to shatter when cooled.

2.1.6. Water droplets in the air duct of the cooling section grille can also cause glass breakage.

2.1.7. Cracking caused by collision between the wind grille and glass during cooling.

2.2. Solution

2.2.1. Adjusting furnace temperature or extending heating time

2.2.2. Balancing furnace temperature and adjusting convection and furnace temperature compensation appropriately

2.2.3. Strictly inspect the quality of tempered glass substrates, and ensure that holes and defects are removed in accordance with standards

2.2.4. Regularly check and clean whether the exhaust system is unobstructed

2.2.5. Conduct quality inspection of the first piece of tempering according to different basic needs and record the tempering process

2.2.6. Adjust the cooling air pressure appropriately

2.2.7. Adjust the wind grille in a timely manner to ensure that the angle of the grille matches the direction of the film.

3. Glass breakage after tempering for a long period of time

3.1. Cause of fragmentation

3.1.1. Tempering glass that has not been fully heated may produce cracks on the surface

3.1.2. Self explosion of nickel sulfide inclusions in glass

3.1.3. Glass edges or glass scratches causing stress imbalance in the glass

3.1.4. Incorrect glass installation method

3.2. Solution

3.2.1. Inspect the finished tempered glass and package it for shipment after passing the inspection.

3.2.2. The glass is homogenized by hot dipping to improve the occurrence of glass self explosion.

3.2.3. Inspect the quality of glass raw materials and use qualified raw materials for tempering treatment

3.2.4. Use the correct installation method for tempered glass installation to avoid glass breakage caused by improper installation.

The above is an explanation of the causes and solutions to the problem of broken tempered glass in the tempering furnace. We hope it can help reduce the losses caused by glass fragmentation in the production process, and improve the yield and quality of glass.