How Is Tempered Glass Made?

Tempered glass—also known as toughened glass—is a premium material trusted across industries for its strength, safety, and durability. From architectural facades to interior partitions, electronic devices to industrial equipment, tempered glass plays a vital role in modern design and engineering. But how exactly is this remarkable material produced?

In this article, we’ll walk you through the complete manufacturing process of tempered glass, highlight the precision involved at each step, and explain why working with a reliable tempered glass manufacturer like Shottglass ensures consistent quality and long-term performance.

1. Selection of High-Quality Base Glass
The tempered glass production begins with selecting a premium float glass sheet. This is a crucial step, as the optical clarity, strength, and safety performance of the final tempered product depend heavily on the quality of the raw glass.

At Shottglass, we only use top-grade float glass with uniform thickness and minimal internal stress to reduce the risk of optical distortion or spontaneous breakage after tempering. Float glass is available in various thicknesses—typically ranging from 2mm (semi-tempered) to 19mm—and must meet strict dimensional tolerance and flatness standards before entering the tempering process.

2. Cutting and Edge Processing
Once the float glass sheets are selected, they are cut to the required size based on the client’s specification. Precision CNC cutting machines are typically used to ensure clean, accurate cuts. Because tempered glass cannot be modified after tempering, all fabrication must be completed beforehand.

After cutting, the edges of the glass must be ground and polished to remove any sharpness and reduce the risk of microcracks or stress concentration points. Options include flat polished, pencil edge, beveled, or seamed edges, depending on the final application.

If the glass requires holes or notches (for mounting hardware or fittings), those are also drilled or milled at this stage using high-speed diamond tools.

3. Cleaning and Inspection
Before entering the tempering furnace, the glass must be thoroughly cleaned to eliminate dust, oil, and debris that could interfere with the tempering process. Industrial washing systems use deionized water and brushes to ensure a spotless surface.

A visual and automated inspection is also carried out to check for imperfections such as chips, scratches, or inclusions. Even the smallest defect can affect the integrity of the tempered glass, so quality control at this stage is critical.

4. Heating in the Tempering Furnace
Next, the clean and prepared glass is fed into a tempering furnace. This furnace uses convection or radiation to heat the glass uniformly to a temperature of approximately 620–680°C (1148–1256°F)—just below the glass's softening point.

Achieving uniform temperature distribution across the entire surface is essential. Uneven heating can result in internal stress imbalances, leading to warping or increased breakage risk after cooling.

5. Rapid Cooling (Quenching)
After reaching the desired temperature, the glass is immediately transferred to the quenching zone. Here, high-pressure blasts of cold air are applied to both sides of the glass, cooling the surface much faster than the core.

This rapid cooling process creates compression on the outer surfaces and tension within the core. It’s this stress profile that gives tempered glass its remarkable strength—up to 5 times that of standard annealed glass—as well as its unique break-safe characteristic: when shattered, it crumbles into small, blunt granules rather than sharp shards.

6. Final Inspection and Quality Assurance
Once tempering is complete, the glass is cooled to room temperature and moved to the inspection area. Each piece undergoes thorough testing to ensure it meets required safety, strength, and optical standards.

Tests include:

Fragmentation test: Confirms the glass breaks into safe, small pieces.
Surface compression test: Measures the stress layer to ensure structural integrity.
Flatness and optical clarity test: Checks for distortion and visual uniformity.

At Shottglass, all tempered glass is produced in compliance with international standards such as EN 12150, ASTM C1048, and CCC, ensuring safety and performance for even the most demanding projects.

7. Optional Custom Coatings or Laminations
In some cases, tempered glass may be treated further after tempering. Options include:

Silk-screen printing or ceramic fritting for decorative or solar-control purposes.
Low-E coatings to enhance energy efficiency in buildings.
Laminating with PVB interlayers for noise reduction, UV protection, or additional security.

These value-added features are typically applied based on the specific needs of the client or project.

Why the Tempering Process Matters

The strength and safety of tempered glass are entirely dependent on the accuracy of the tempering process. Improper heating, uneven cooling, or poor-quality raw materials can result in high spontaneous breakage rates, surface waviness, and optical distortion—all of which reduce the reliability of the final product.

By working with a trusted tempered glass supplier like Shottglass, clients benefit from:

State-of-the-art production equipment
Skilled technicians and engineers
Strict in-house quality control
OEM and custom-size capabilities
Competitive tempered glass pricing

Conclusion

Tempered glass is more than just glass—it’s a performance material built through precision engineering and careful processing. From initial float glass selection to final inspection, every step in the manufacturing process is essential to ensuring the strength, safety, and reliability of the end product.

Whether you’re sourcing tempered glass for architectural projects, automotive components, or high-end interior installations, understanding how tempered glass is made helps you appreciate its value—and the importance of choosing a quality manufacturer.

With decades of experience and a proven track record in global markets, Shottglass is your trusted partner for high-quality tempered glass solutions made in China.