Tempered glass is a type of safety glass that has been heat-treated in a tempering furnace to enhance its strength and thermal resistance. Today, tempered glass is widely manufactured and used across the globe. In this article, LandGlass brings you a closer look at how float glass is transformed into tempered glass through the tempering process.
Step 1: Selecting the Glass
Choose flat float glass of the appropriate size. The typical glass thickness used ranges from 4 to 19 mm, with dimensions from 150 mm × 200 mm up to 3000 mm × 8000 mm.
Step 2: Cutting the Glass to Size
Glass sheets are transferred by machine to an automatic cutting table. CNC-controlled cutting machines cut the raw glass into desired shapes based on customer orders. Please note all preprocessing must be completed before tempering, as tempered glass cannot be cut or drilled after tempering treatment.
Step 3: Edge Grinding and Drilling
Depending on the order specifications, the cut glass undergoes edge grinding and CNC waterjet drilling to achieve the required shapes and holes.
Step 4: Washing the Glass
The glass then goes through a washing machine to remove any micro-glass particles and dust left from earlier processing stages. This ensures surface cleanliness, which is essential for high-quality tempering.
Step 5: Heating in the Tempering Furnace
The glass is heated to around 630°C inside the tempering furnace. The heating time varies based on factors such as glass thickness, color, and even ambient temperature. On average, it takes between 2 to 25 minutes to reach the proper temperature.
Step 6: Rapid Cooling (Quenching)
After heating, the glass moves into the quenching section, where high-pressure air is blown onto it from multiple angles for several seconds to minutes. This rapid cooling causes the surface of the glass to solidify faster than the center, creating compressive stress on the surface and tensile stress inside—the key to tempered glass's strength and safety properties.
Step 7: Packaging, Storage, and Delivery
The finished tempered glass is placed on storage racks to cool naturally before being carefully packed. Once packaged, the glass is ready for storage or delivery to customers.