Tungsten wire is often used in glass heating process due to its high melting point (about 3422°C), high strength and good thermal stability, especially in scenes requiring high temperature environment.
I. Scope of Application of Tungsten Wire for Glass Heating
1. Glass Melting and Forming:
Tungsten wire is often used in glass melting furnaces or heating equipment as an electric heating element to melt glass raw materials (such as quartz glass, borosilicate glass, etc.). Its high temperature resistance makes it suitable for high temperature melting environment (usually 1200°C to 2000°C).
It is used in processes such as glass fiber drawing and glass tube/rod forming to heat the glass to a plasticized state.
2. Glass Annealing:
After the glass products are formed, the tungsten wire heater can be used in the annealing furnace to provide a uniform heat field to eliminate the internal stress of the glass and prevent cracking. Annealing temperature is usually between 400°C and 800°C, and tungsten wire can work stably.
3. Glass Sealing and Welding:
In the sealing process of glass to metal or glass to glass, tungsten wire can be used for local high-temperature heating (such as vacuum tube and light bulb manufacturing) to ensure that the glass softens in a specific area and forms an airtight connection.
4. Laboratory and Special Glass Processing:
In the laboratory or special glass (such as optical glass, quartz glass) processing, tungsten wire heaters are used in small heating equipment to accurately control the temperature, which is suitable for small batches or high-precision processes.
5. Vacuum or Protective Atmosphere Environment:
Tungsten wire is suitable for heating glass in a vacuum or inert gas (such as argon, nitrogen) environment. Because it is easy to oxidize at high temperatures, it must be avoided from contact with oxygen.
II. Use Conditions and Limitations of Tungsten Wire for Glass Heating
1. Temperature Range: Tungsten wire can be used in heating environments up to 2000°C, but the actual use temperature is usually limited by the glass type and process requirements.
2. Environmental Requirements: It needs to be operated in a vacuum or inert atmosphere to prevent oxidation of the tungsten wire. When used in air, the temperature needs to be controlled in a lower range (<500°C) or a protective coating should be used. 3. Power and Design: The design of the tungsten filament heater needs to consider the thermal conductivity and thermal expansion coefficient of the glass to avoid local overheating or thermal stress that causes glass breakage. 4. Life and Maintenance: Tungsten filaments may experience grain growth or embrittlement at high temperatures and need to be inspected and replaced regularly.
