Latest in Glastory: No more flat thinking for a curved world

by Juha Karisola

Bent and tempered glass has long been of great interest to the market. The process of creating high-quality tempered bent glass has evolved over the years. Continued research and development, the best use of the latest technology and the experience of industry experts have opened up new dimensions in glass.

Such a common material is glass that it’s easy to forget we still don’t understand its full capabilities. Bent glass has been used in buildings since the early nineteenth century. But it wasn’t until the 1990s, with the development of the first horizontal tempering machine with a bending furnace, that bent tempered glass of sufficiently good optical quality became generally available. Still, there were quite a few limitations and constraints.

Many efforts have been made to improve the technology over the last years, to improve methods and techniques of processing tempered bent glass and also to process top quality.

The bending and tempering process in brief

Modern horizontal bending and tempering lines commonly operate like this:

  1. The flat glass is first heated to over 630 °C − until red hot.
  2. Once heated, the glass is moved within the furnace into the bending station, where it is bent to its target radius.
  3. The glass can be twisted into the direction in which the glass flows, which is known as lengthwise bending.
  4. It can also be bent crosswise across the glass flow, which is called crosswise bending.
  5. The bent glass is then tempered by cooling to trap high energy forces within the glass.
  6. The bent and tempered glass comes out of the furnace.

It’s fair to say the main stages of this process have not changed much since the 90s. But technologies have.
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