+86 18737971827 396041848@qq.com

Home News

What is a glass tempering furnace?
24 May. 2024

What is a glass tempering furnace?

Glass Tempering Furnaces Introduction

Glass tempering furnaces are essential in the glass manufacturing industry, enabling the production of tempered glass, which is significantly stronger than regular annealed glass. This article explores the technical aspects of glass tempering furnaces, including their design, operation, types, and maintenance.

Principles of Glass Tempering

Glass tempering involves heating glass to a temperature just below its melting point (approximately 600-650°C) and then rapidly cooling it. This process induces compressive stresses on the surface and tensile stresses inside, resulting in increased strength and improved safety characteristics. Tempered glass shatters into small, blunt pieces rather than sharp shards.

Components of a Glass Tempering Furnace

glass tempering furnace

Heating Section

Heating Elements: Typically made from high-resistance alloys such as Kanthal (FeCrAl) or Nickel-Chromium (NiCr) alloys. These elements provide consistent and uniform heating.

Insulation: High-quality refractory materials like ceramic fiber boards or alumina-silicate bricks are used to insulate the furnace, reducing heat loss and improving energy efficiency.

Temperature Control: Advanced control systems, often employing thermocouples and infrared sensors, ensure precise temperature regulation throughout the heating chamber.

Quenching Section

Air Blowers: Powerful fans generate high-pressure air streams for rapid cooling. The airflow must be uniform and controllable to achieve the desired stress profile in the glass.

Nozzles: Specially designed nozzles distribute air evenly across the glass surface. The nozzle arrangement and size are critical for achieving uniform cooling.

Conveyor System

Rollers: Heat-resistant rollers, often made from fused silica or ceramic-coated steel, transport the glass through the furnace. The roller speed is adjustable to control the heating and cooling rates.

Drive Mechanism: Precision motors and drives ensure smooth and consistent movement of glass through the furnace.

Types of Glass Tempering Furnaces

Horizontal Tempering Furnaces

Operation: Glass moves horizontally through the furnace on rollers.

Applications: Suitable for flat glass panels used in windows, doors, and automotive applications.

Advantages: Reduced risk of glass surface damage and higher throughput.

Vertical Tempering Furnaces

Operation: Glass is suspended vertically during the tempering process.

Applications: Used for thinner or specialty glass shapes, such as shower doors and architectural panels.

Advantages: Lower space requirements and ability to handle more complex shapes.

glass tempering furnace

Technical Specifications

Maximum Glass Thickness: Typically ranges from 3mm to 19mm.

Cycle Time: Varies depending on glass thickness and furnace type, generally ranging from 2 to 5 minutes per sheet.

Heating Capacity: Furnaces can handle glass sizes from small panels to large sheets up to 3.3m x 6m.

Energy Consumption: Efficiency improvements are continually sought, with modern furnaces incorporating energy recovery systems to reduce consumption.

Operation and Control

Pre-Heating Phase

Loading: Glass sheets are loaded onto the conveyor system.

Initial Heating: The glass is gradually heated to avoid thermal shock.

Heating Phase

Uniform Heating: The temperature is raised to the tempering range (600-650°C), ensuring uniform heat distribution across the glass surface.

Temperature Monitoring: Continuous monitoring and adjustment maintain the desired temperature profile.

Quenching Phase

Rapid Cooling: The glass is quickly transferred to the quenching section, where high-pressure air cools it rapidly.

Stress Formation: Controlled cooling induces the necessary stress distribution for tempered glass.

Post-Quenching Phase

Unloading: Tempered glass is carefully removed from the conveyor system.

Inspection: Visual and automated inspections check for quality and stress uniformity.

Glass tempering furnace

Maintenance and Troubleshooting

Regular Maintenance

Heating Elements: Periodically inspect and replace worn heating elements to maintain consistent performance.

Insulation: Check and repair any damaged insulation to prevent heat loss.

Conveyor System: Lubricate and inspect rollers and drive mechanisms to ensure smooth operation.

Air Blowers and Nozzles: Clean and inspect to ensure uniform airflow during quenching.


Temperature Variations: Address issues with heating elements or control systems to maintain uniform temperature.

Airflow Inconsistencies: Ensure blowers and nozzles are functioning correctly to avoid uneven cooling and stress distribution.


Glass tempering furnaces are critical for producing high-strength, safety-enhanced glass. Understanding the technical specifications and operational considerations of these furnaces is essential for optimizing performance and ensuring product quality. Regular maintenance and precise control of the heating and quenching processes are vital to achieving the desired properties in tempered glass. As technology advances, glass tempering furnaces continue to evolve, offering improved efficiency, capacity, and control for the glass manufacturing industry.