Part 2 of Glass tempering basics series
There’s a Finnish saying: “A beloved child has many names.” In the glass industry, that child is convection. Everyone talks about it — full convection, forced convection, assisted convection, high convection… the list goes on. But what really matters?
What is convection in tempering?
Convection is simply the transfer of heat through air movement. It’s a key player in efficiently heating glass, especially when coatings reduce the effectiveness of radiation. But here’s the truth: glass doesn’t care about the technology behind convection — it cares about results.
Two main technologies
- Compressed Air Convection
- Recirculated Air Convection
These terms describe how convection is created, not how well it performs. A recirculated-air furnace isn’t automatically better than a compressed-air one. Marketing terms like “full” or “high” convection? They sound fancy, but every furnace still uses both conduction and radiation.
What should you focus on?
- Performance, not labels: Heating accuracy and speed define glass quality — not the convection type.
- Your production needs: Choose technology that delivers repeatability, capacity, and reliability for your line.
- Don’t generalize: Not all furnaces using the same convection method perform the same.
We have written a whole eBook on the topic. So, if convection furnaces are of interest to you, we recommend that you download the eBook – it’s free!
Coming up next:
In Part 3, we’ll dive into cooling technology and why pre-processing is the unsung hero of glass tempering. Curious how cooling impacts strength and safety? Stay tuned!