Tempered Glass is annealed glass that has been heated up to atleast 627°C and then rapidly cooled. The glass surface becomes 4-5 times as strong as annealed glass after the process has completed. The term ‘Toughened Glass’ has exactly the same meaning as ‘Tempered Glass’.
How is the tempering process done?
In a nutshell, Tempering is achieved by running a sheet of flat/ plate glass through a Toughening Plant / Tempering Furnace. The plant has a series of rollers that takes the glass from the loading area through two chambers. The first chamber is the oven that heats up the plate glass evenly until it reaches 627°C .
Once this temperature is achieved, it is then carried through to the cooling chamber where the glass is then cooled down (quench) in a even and controlled manner.
The final destination for the glass is to the unloading area at the far end of the plant. An operator will check or inspect the glass visually at this point. Checks include that the glass will be perfectly flat and not curved in any way.
What size glass can be tempered?
Generally a glass processing factory will pass through glass with atleast one of its dimensions of 300mm and the other dimension 40mm or so. Glass smaller than this can fall through the rollers or simply ‘blow up’ in the heating process.
The largest commercial Toughening plants will accept plate glass of 3000mm x 6000mm or a ‘Jumbo Sheet’
Regarding thickness, glass in a regular toughening plant can toughen from 3mm up to a staggering 19mm in thickness. Times will vary when tempering. The thicker the glass the longer the whole process takes.
Where can I find tempered glass?
The most common uses for Tempered glass are:
- Shower screens
- Table Tops
- Glass walls/ Partition systems
- Hospitality screens and guards
- Hearths for Fireplaces
The above process ultimately refers to Architectural glass.
So, where else can I find Tempered glass? The chances are you are probably using a phone now to read this? If that is the case then the glass will be toughened also. Others include:
- Automotive glass
- Glass Tumblers
- Oven Glass
- Diving Masks
- Chopping boards
- Fridge Shelves
- Sight Glass
- Ipads/ Mobile devices
You can find a tempering furnace at most glass processing manufacturers. They have a big range of Bed sizes.
Bed sizes can be from as little at 8-10 meters in length up to some automated tempering furnaces in excess of 40 meters in length!
If you were looking to purchase a furnace then you better set back a few hundred thousand dollars or Pounds depening on where you live. That would be for a regular plant, jumbo or multi line furnaces can set you back in excess of $2m…
For rescorces or more info, pop over to a few manufacturers below.
Photo Credits – Landglass, Ervin