Chemical tempering service
Chemically tempered glass refers to glass whose mechanical strength is improved by replacing the alkali metal ions on the surface of the glass with other alkali metal ions in the molten salt through ion exchange.
Our chemical strengthening Glass Manufacturing Capabilities
Our factory specializes in chemical strengthening for explosion-proof lenses. Using proprietary chemical baths developed through years of R&D, we enhance surface strength, thermal shock resistance, and durability. This in-house process ensures superior performance, meeting strict requirements for impact (e.g., 5J+) and extreme temperatures. Trust our expertise for reliable, custom-strengthened glass solutions.
Advanced Hot-End Chemical Strengthening
Instant Hot Immersion: Proprietary process strengthens glass right after molding at 500°C+.
Proven Performance: Withstands 120°C thermal shock & 5J+ impacts.
Superior Durability: Enhanced surface compression ensures long-term chemical & abrasion resistance.
Chemical Strengthening Capabilities for Flat Glass
Deep Surface Compression: Achieves 700+ MPa surface stress for exceptional impact and load resistance.
High Thermal Stability: Maintains integrity under thermal shocks from -50°C to 250°C.
Optical Clarity Preservation: Near-zero distortion with >92% light transmission rates.
Chemical tempering classification
Chemical Strengthening via Ion Exchange I
Using low-temperature molten salt ion exchange technology (320-380℃, K⁺/Na⁺ exchange, 8-16 hours of treatment), a 15-25μm compressive stress layer is formed on the glass surface, and the microhardness reaches HV450 -550. This grade is suitable for building door and window glass (meeting EN 12600 Class B impact resistance standard), furniture laminates (load ≤200kg/m²), and home appliance panels (such as oven doors). It is economical and safe, with a unit energy consumption of 12-18kWh/㎡ and a potassium nitrate consumption of 0.5-0.8kg/㎡, which can balance mass production needs and basic protection performance.
Chemical Strengthening via Ion Exchange II
Through the mixed molten salt method (KNO₃+NaNO₂, 380-420℃/4-8h), 25-50μm deep strengthening is achieved, the microhardness is increased to HV600-750, and the surface roughness Ra≤0.02μm after optical polishing. It is specially designed for smartphone cover plates (1m drop pass rate＞95%), vehicle-mounted central control screens (7H pencil hardness scratch resistance) and industrial instrument windows (impact resistance≥5J), supports 2.5D micro-arc edge precision processing (R angle≥0.3mm), and shows excellent performance in complex curved surfaces and high light transmittance demand scenarios.
Chemical Strengthening via Ion Exchange III
Based on electric field-assisted ion exchange technology (450℃/5kV/m, 1-3h short-time treatment), a 50-100μm gradient stress layer (gradient ≤8MPa/μm) is generated, the microhardness exceeds HV800-1000, and the stress decay is less than 5% after a 300℃/2h high-temperature test. For cutting-edge fields: folding screen UTG (3mm bending radius/200,000 cycles), UL 752 Level 5 bulletproof glass (anti-bullet speed ≥650m/s) and high-energy laser devices (damage threshold>10J/cm²), stress distribution is strictly verified by X-ray diffraction (XRD), providing a nano-precision safety barrier for extreme environments.
Our factory and our partner factories
BO-GLASS coordinates our core facility with a dedicated network of local specialists to deliver custom glass components. You benefit from our collective expertise while we manage all communication, quality control, and logistics for a seamless experience.
Inquiry and Confirmation
Receive and confirm the customer’s inquiry, ensuring accurate specifications and information.
Quotation and Sample Preparation
Prepare and send the quotation. Once confirmed by the customer, create the sample.
Sample Delivery and Feedback
Deliver the sample to the customer, gather feedback, and confirm the sample meets requirements.
Bulk Order Confirmation and Production
Once the sample is approved, confirm the bulk order, verify details, and start mass production.
Quality Inspection and Packaging
Conduct quality checks after production to ensure standards are met and packaged as required.
Shipping and Delivery
Glass Tempering Process & Purpose
Chemical strengthening submerges glass in molten salt, creating a permanent compression layer that boosts impact resistance 3-5x while maintaining optical clarity. This process transforms standard glass into durable, safe components for architecture, appliances, explosion-proof lighting, and electronic displays.
Our Custom Glass Fabrication Portfolio: See Our Success Stories
Explore our portfolio of bespoke glass projects. Each piece showcases our expertise in delivering precision-engineered custom glass solutions for clients across diverse industries and applications.
Chem Strengthened Ultra Clear Glass Cover
White edge printed ultra-clear glass for LED strips.
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Explosion-Proof Chem Strengthened Airport Signal Light Cover
Chemically strengthened, heat shock resistant lens for airport lighting. Enhanced safety & durability.
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Chem Strengthened Ultra-Clear Step Glass for Architectural LED
Tempered safety glass panel for explosion-proof control cabinets. Withstands 4J impact test.
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4J Impact Rated Tempered Glass for Explosion-Proof Cabinet
Tempered safety glass panel for explosion-proof control cabinets. Withstands 4J impact test.
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Drilled & Silkscreened 4J Impact Tempered Explosion-Proof Glass
Custom drilled, silkscreened tempered glass for explosion-proof security equipment. Resists 4J impact.
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White Silkscreened Tempered Glass Panel for Smart Appliances
Custom white edge silkscreen with logo on tempered glass for smart control panels. Scratch-resistant.
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Tempered Glass Panel with Perimeter Silk-Screening Edge Printing
Chemically strengthened glass with edge printing. Withstands 5J impacts and 300°C thermal shock for durable displays.
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Square Appliance Glass Panel with Edge Printing & Tempering
Chemically strengthened square glass with perimeter silk-screening. Resists 5J impacts and 300°C thermal shock for control panels.
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Tempered Borosilicate Gauge Plate for Klinger Test Lens
Low thermal expansion (3.3×10⁻⁶/K), withstands 400°C thermal shock. Precision flatness under 2μm for optical testing instruments.
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Tempered Round Glass Panel with Black Silk-Screening & Mounting Holes
5J impact-resistant, withstands 300°C thermal shock. Black perimeter printing for lighting fixtures with secure mounting holes.
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Chemically tempered glass classification
(1) According to the usage, it can be divided into chemically tempered glass for construction, which is used as partitions in buildings or indoors, marked as CSB; chemically tempered glass for use outside buildings, such as chemically tempered glass for instruments, optical instruments, copiers, home appliance panels, etc., marked as CSOB.
(2) The surface stress value can be divided into Class I, Class II, and Class III (see Table 4-1).
Table 4-1: Surface Stress of Chemically Tempered Glass
| Category | Surface Stress (p/MPa) |
|---|---|
| Class I | 300 < p ≤ 400 |
| Class II | 400 < p ≤ 600 |
| Class III | p > 600 |
(3) According to the thickness of the compressive stress layer, it can be divided into Class A, Class B, and Class C, see Table 4-2.
Table 4-2: Compressive Stress Layer Thickness of Chemically Tempered Glass
| Category | Compressive Stress Layer Thickness (d/μm) |
|---|---|
| Class A | 12 < d ≤ 25 |
| Class B | 25 < d ≤ 50 |
| Class C | d > 50 |
(4) According to the production process, it can be divided into surface dealkalization, high expansion glass surface coated with low expansion glass, alkali metal ion exchange, and other methods. Among them, alkali metal ion exchange can be divided into high-temperature ion exchange and low-temperature ion exchange. At present, alkali metal ion exchange is the main production process of chemically tempered glass.
Performance characteristics of chemically tempered glass
① Chemically tempered glass is a reinforced glass that has been achieved through an ion exchange process. The ion exchange process can effectively improve the mechanical strength of glass and is especially suitable for strengthening ultra-thin, small-sized, or complex-shaped glass products. After ion exchange treatment, the glass will not produce directional optical deformation. The bending strength is 200~350MPa, and the impact strength of 3mm chemically tempered glass is 3.5~4.0m (227g steel ball), which is about 3 times that of physical tempering.
② Although the surface compressive stress of chemically tempered glass is very high, the intermediate tensile stress that balances it is very small, so chemically tempered glass does not have the phenomenon of self-explosion. The thickness of the surface compressive stress layer is generally 10~200μm, and the compressive stress is 300~500MPa, which is 3~5 times higher than the physical tempering compressive stress of 100MPa.
③ Chemically tempered glass must maintain a certain exchange layer depth, and the exchange layer depth will increase with the extension of exchange time, but the surface compressive stress will reach the maximum value with the extension of exchange time, and then gradually decrease.
③ Chemically tempered glass must maintain a certain exchange layer depth, and the exchange layer depth will increase with the extension of exchange time, but the surface compressive stress will reach the maximum value with the extension of exchange time, and then gradually decrease.
④ Chemically tempered glass made from a single piece of ordinary annealed glass through ion exchange is not safety glass. The state of its fragments after breaking is similar to that of ordinary annealed glass after breaking. When it is used in places involving personal safety, it needs to be further processed, such as laminated glass.
⑤ Chemically tempered glass can be cut, but the new cut edge will cause a decrease in strength. Therefore, the required pre-treatment process needs to be completed before chemical tempering.
⑥ The ion exchange process changes the surface properties of the glass. Therefore, the subsequent processing process (such as interlayer or coating) of chemically tempered glass will be different from that of non-chemically tempered glass.
⑤ Chemically tempered glass can be cut, but the new cut edge will cause a decrease in strength. Therefore, the required pre-treatment process needs to be completed before chemical tempering.
⑥ The ion exchange process changes the surface properties of the glass. Therefore, the subsequent processing process (such as interlayer or coating) of chemically tempered glass will be different from that of non-chemically tempered glass.
The stress distribution of chemically tempered glass is shown in Figure 4-1.
Chemical tempering principle
Glass is an amorphous solid substance. Generally, silicate glass is composed of a network formed by Si-0 bonds and alkali metal, alkaline earth metal ions entering the network. This network is composed of polyhedrons (trihedrons or tetrahedrons) containing oxygen ions, and its center is occupied by Si⁴+, Al³+, or P⁵+. Among them, alkali metal ions are more active and are easily precipitated from the inside of the glass. The ion exchange method is based on the natural diffusion and mutual diffusion of alkali metal ions to change the composition of the surface layer of glass, thereby forming a surface compressive stress layer.
When the glass is immersed in a molten salt solution, ion exchange occurs between the glass and the salt solution. Some alkali metal ions near the surface of the glass diffuse into the molten salt, and their vacancies are occupied by alkali metal ions of the molten salt. As a result, the chemical composition of the surface layer of the glass is changed, and its thermal expansion coefficient is reduced, thereby forming a surface compressive stress layer of 10~200μm. Because of the existence of this surface compressive stress layer in glass, when external force acts on this surface, this part of the compressive stress must be offset first, thus improving the mechanical strength of the glass; because the thermal expansion coefficient of the glass is reduced, its thermal stability is improved. These are the reasons why chemically tempered glass can improve its mechanical strength and thermal stability.
When the glass is immersed in a molten salt solution, ion exchange occurs between the glass and the salt solution. Some alkali metal ions near the surface of the glass diffuse into the molten salt, and their vacancies are occupied by alkali metal ions of the molten salt. As a result, the chemical composition of the surface layer of the glass is changed, and its thermal expansion coefficient is reduced, thereby forming a surface compressive stress layer of 10~200μm. Because of the existence of this surface compressive stress layer in glass, when external force acts on this surface, this part of the compressive stress must be offset first, thus improving the mechanical strength of the glass; because the thermal expansion coefficient of the glass is reduced, its thermal stability is improved. These are the reasons why chemically tempered glass can improve its mechanical strength and thermal stability.
Our applications of glass processing technology
We are committed to providing our customers with one-stop solutions, from prototype development to mass production, by addressing the entire value chain of materials science, engineering design, and precision manufacturing. Our goal is to transform the ultimate performance of glass materials into a core competitive advantage for your products.
Precision Medical Prototypes & Labware Manufacturing
We provide high-quality custom medical prototypes and labware with on-demand production at competitive prices to accelerate your launch.
Explosion-Proof Lighting Glass for Hazardous
Custom heat-resistant glass for outdoor lighting. From precise prototypes to full-scale production, we can assist you every step of the way.
Electronices&Home appliance instruments products Prototyping
Quality manufacturing for electronics & appliances, from prototypes to production. On-demand to accelerate launch & reduce risks.
Glass Lampshade Manufacturing
We offer high-quality production of custom indoor glass lampshades. Launch elegant designs faster and reduce risks with our reliable, on-demand manufacturing.
Trustworthy expert in glass manufacturing solutions
AtBO-GLASS, our quality control begins with comprehensive design review and DFM analysis to optimize manufacturability. Throughout production, we implement rigorous process controls with material certification and in-process verification.
We utilize advanced metrology equipment including CMM, spectrophotometers, polariscopes, and surface roughness testers to validate dimensional accuracy, optical properties, stress distribution, and surface quality.
Our quality assurance includes first-article inspection, dimensional verification, and functional testing. Each component undergoes final inspection by certified technicians. Certified to ISO 9001:2015, we guarantee all components meet the highest standards for precision and reliability in every delivery.
BO-GLASS Product Release Standard
All glass components undergo strict verification. Each order includes an inspection report confirming compliance.
Surface Quality: Smooth and uniform, free from pits or cracks. Minimal mold contact marks are acceptable.
Dimensional Integrity: Consistent contour and thickness with tight tolerances.
Material Clarity: High-quality optical materials ensure excellent clarity and uniformity.
Cleanliness: All parts are thoroughly cleaned, free from residues or visible handling marks.
Surface Quality: Smooth and uniform, free from pits or cracks. Minimal mold contact marks are acceptable.
Dimensional Integrity: Consistent contour and thickness with tight tolerances.
Material Clarity: High-quality optical materials ensure excellent clarity and uniformity.
Cleanliness: All parts are thoroughly cleaned, free from residues or visible handling marks.
Related knowledge
We have an extensive range of online resources developed to help worker improve their capabilities.
Methods to improve chemical tempering efficiency
Improving the efficiency of chemical tempering is actually to accelerate ion exchange. In addition to adding accelerators to molten salt, the more mature and commonly used methods in the industry are the two-stage treatment method and the electrochemical method.
(1) Two-stage treatment method The one-time treatment method is to treat the sodium-lime-silicon system glass in KNO₃ molten at 450℃ for 38 hours, forming a 40μm thick compressive stress layer, and enhancing the flexural strength to 294MPa.
The two-stage treatment method, that is, to treat twice in K+ molten salt solutions of different components, can greatly reduce the treatment time to obtain the same strengthening effect. The method is to firstly immerse the glass in a mixed salt composed of Na₂SO453.81% and K₂O46.19% at a temperature of 600℃, treat it for 25 minutes, and then put it in pure KNO₃ molten salt at a temperature of 450℃ for 10.5 hours. After treatment, the flexural strength of the glass increases to 313.6MPa, while the treatment time is greatly reduced, and the total treatment time is only 11 hours.
The two-stage treatment method, that is, to treat twice in K+ molten salt solutions of different components, can greatly reduce the treatment time to obtain the same strengthening effect. The method is to firstly immerse the glass in a mixed salt composed of Na₂SO453.81% and K₂O46.19% at a temperature of 600℃, treat it for 25 minutes, and then put it in pure KNO₃ molten salt at a temperature of 450℃ for 10.5 hours. After treatment, the flexural strength of the glass increases to 313.6MPa, while the treatment time is greatly reduced, and the total treatment time is only 11 hours.
(2) Electrochemical method The electrochemical method is a method that uses additional voltage to perform ion exchange in an electric field to accelerate the diffusion of ions.
The process of the electrochemical method is roughly as follows: an anode is installed at one end of the molten salt tank and a cathode is installed at the other end. Soda-lime-silicon system glass is infiltrated into the KNO₃ molten salt. After the glass is infiltrated, a partition is formed in the electric field, dividing the molten salt into two parts, the anode and the cathode. The electric field is perpendicular to the glass surface, which accelerates the diffusion of K+ on the anode side of the molten salt to the glass surface. At the same time, it also promotes the migration of the same amount of Na+ out of the glass on the cathode side of the same electric field.
The disadvantage of the electrochemical method is that only one surface of the glass can be processed at a time. To complete the tempering of the entire piece of glass, the anode and cathode must be changed alternately to process the surface of the glass so that ions can be exchanged alternately on both sides of the glass.
The process of the electrochemical method is roughly as follows: an anode is installed at one end of the molten salt tank and a cathode is installed at the other end. Soda-lime-silicon system glass is infiltrated into the KNO₃ molten salt. After the glass is infiltrated, a partition is formed in the electric field, dividing the molten salt into two parts, the anode and the cathode. The electric field is perpendicular to the glass surface, which accelerates the diffusion of K+ on the anode side of the molten salt to the glass surface. At the same time, it also promotes the migration of the same amount of Na+ out of the glass on the cathode side of the same electric field.
The disadvantage of the electrochemical method is that only one surface of the glass can be processed at a time. To complete the tempering of the entire piece of glass, the anode and cathode must be changed alternately to process the surface of the glass so that ions can be exchanged alternately on both sides of the glass.
Chemically tempered glass quality requirements and testing
Thickness deviation requirements and measurement methods
(1) Thickness deviation requirements The thickness deviation of chemically tempered glass shall comply with the provisions of Table 4-7.
(2) Testing method Use an outside micrometer with an accuracy of 0.01 mm or an instrument with the same accuracy to measure at the midpoint of the four sides within 15 mm from the edge of the glass plate. The arithmetic mean of the measurement results is the thickness value, and it is rounded to one decimal place.
(2) Testing method Use an outside micrometer with an accuracy of 0.01 mm or an instrument with the same accuracy to measure at the midpoint of the four sides within 15 mm from the edge of the glass plate. The arithmetic mean of the measurement results is the thickness value, and it is rounded to one decimal place.
Table 4-7: Thickness and Permissible Deviation (Unit: mm)
| Thickness (mm) | Permissible Deviation |
|---|---|
| 2, 3, 4, 5, 6 | -0.2 |
| 8, 10 | ±0.3 |
| 12 | ±0.4 |
Dimensional deviation requirements and measurement methods
(1) Dimensional deviation requirements For rectangular chemically tempered glass for architectural use, the allowable deviation of its length and width dimensions shall comply with the provisions of Table 4-8. For chemically tempered glass of other shapes and use other than architectural use, the dimensional tolerance shall be agreed upon by the supplier and the buyer.
(2) Testing method: Measure with a steel tape measure with a minimum scale of 1 mm.
(2) Testing method: Measure with a steel tape measure with a minimum scale of 1 mm.
Table 4-8: Dimensional Permissible Deviation (Unit: mm)
| Glass Thickness (mm) | L ≤ 1000 | 1000 < L ≤ 2000 | 2000 < L ≤ 3000 | L > 3000 |
|---|---|---|---|---|
| < 8 | +1 / -2 | ±3.0 | ±3.0 | ±4.0 |
| ≥ 8 | +2 / -3 |
Diagonal deviation requirements and measurement methods
(1) Diagonal deviation requirements For rectangular chemically tempered glass products, the diagonal difference should not exceed the requirements of Table 4-9.
(2) Testing method: Measure with a steel tape measure with a minimum scale of 1 mm.
(2) Testing method: Measure with a steel tape measure with a minimum scale of 1 mm.
Table 4-9: Permissible Diagonal Deviation for Rectangular Chemically Tempered Glass (Unit: mm)
| Glass Thickness (mm) | Edge Length ≤ 2000 | 2000 < Edge Length ≤ 3000 | Edge Length > 3000 |
|---|---|---|---|
| 3, 4, 5, 6 | ±3.0 | ±4.0 | ±5.0 |
| 8, 10, 12 | ±4.0 | ±5.0 | ±6.0 |
Appearance quality requirements and testing methods
(1) Appearance quality requirements The appearance quality of tempered glass shall meet the requirements specified in Table 4-10.
Table 4-10: Appearance Quality Requirements
| Defect Name | Description | Permissible Number of Defects |
|---|---|---|
| Edge Chipping | Each meter of edge length per glass piece may have chips no longer than 10 mm, with a depth extending from the edge toward the surface no greater than 2 mm, and extending into the thickness no greater than 1/3 of the glass thickness. | 1 occurrence |
| Scratches | Minor scratches less than 0.1 mm in width, permissible number per square meter when length ≤ 60 mm. | 4 scratches |
| Cracks and Missing Corners | Not allowed. | 0 |
| Stains and Smudges | Chemically tempered glass should not have visible stains or smudges. | 0 |
Round hole processing requirements and testing
Round hole processing is only applicable to tempered glass with a nominal thickness of not less than 4 mm. The edge processing quality of the round hole shall be agreed upon by the supplier and the buyer.
(1) Aperture The aperture shall generally not be less than the nominal thickness of the glass, and the allowable deviation of the aperture shall comply with the provisions of Table 4-11. The allowable deviation of the aperture of holes less than the nominal thickness of the glass shall be agreed upon by the supplier and the buyer.
(2) For the position of the hole, refer to “the position of hole ②” in 3.5.3(2) of this book.
(3) The detection method is to measure with a vernier caliper with a minimum scale of 0.1 mm.
(1) Aperture The aperture shall generally not be less than the nominal thickness of the glass, and the allowable deviation of the aperture shall comply with the provisions of Table 4-11. The allowable deviation of the aperture of holes less than the nominal thickness of the glass shall be agreed upon by the supplier and the buyer.
(2) For the position of the hole, refer to “the position of hole ②” in 3.5.3(2) of this book.
(3) The detection method is to measure with a vernier caliper with a minimum scale of 0.1 mm.
Table 4-11: Hole Diameter and Permissible Deviation (Unit: mm)
| Nominal Hole Diameter (D) | Permissible Deviation |
|---|---|
| D < 4 | To be agreed upon by both supplier and customer |
| 4 ≤ D ≤ 50 | ±1.0 |
| 50 < D ≤ 100 | ±2.0 |
| D > 100 | To be agreed upon by both supplier and customer |
Thermal shock resistance requirements and testing
(1) Heat shock resistance requires that chemically tempered glass should withstand a temperature difference of 120℃ without being damaged.
(2) Testing method: Place a 300mm×300mm tempered glass sample in an oven at (120±2)℃ and keep it warm for more than 4 hours. After taking it out, immediately immerse the sample vertically in a 0℃ ice-water mixture, ensuring that 1/3 to 2/3 of the sample height is immersed in water. After 5 minutes, observe whether the glass is damaged.
Take 3 samples for testing. When all 3 samples meet the requirements, the performance is considered qualified. When two or more samples do not meet the requirements, it is considered unqualified. When one sample does not meet the requirements, add 3 more samples. If all meet the requirements, it is qualified.
(2) Testing method: Place a 300mm×300mm tempered glass sample in an oven at (120±2)℃ and keep it warm for more than 4 hours. After taking it out, immediately immerse the sample vertically in a 0℃ ice-water mixture, ensuring that 1/3 to 2/3 of the sample height is immersed in water. After 5 minutes, observe whether the glass is damaged.
Take 3 samples for testing. When all 3 samples meet the requirements, the performance is considered qualified. When two or more samples do not meet the requirements, it is considered unqualified. When one sample does not meet the requirements, add 3 more samples. If all meet the requirements, it is qualified.
Our other manufacturing capabilities
We can provide you with a variety of glass processing techniques.
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