Bending as a key factor in windshield manufacturing

Juha Karisola - Windshield bending technologies have developed since the first commercial pieces of glass were bent at the end of the 1940s.

The simple one-directional bending method didn’t require much from technology.  Yet the first double curves introduced in the late 1950s started an evolution that continues today. Although there are many sub-processes involved, the key technique for optical quality and shape accuracy is the bending process. Without perfect bending, the whole process fails. There are three bending processes that are in use today: gravity bending, press bending and press-assisted bending.

Gravity bending

Gravity bending is a cost-effective process to create any shapes, even deeper sags, wrap-around corners and also when a wider variety of coating options are needed. Gravity bending is best used for short series because many different types of molds can be used simultaneously in the process. This makes it the best bending process for automotive replacement glass manufacturers (AGRs) as only one mold is required for short runs.

Earlier, shaping was difficult because heat came only from above. Now with the latest technology, focused overall heating with power regulation and double-actuated molds with triggering devices allow much more precise shape control resulting in better end quality.

Press bending

From a process point of view, press-based bending systems are simple and don’t require focused heating or complicated molds. There are only two phases in the process: heating the glass in a furnace and using molds to press it into the desired shape. This bending process gives very high output, good repeatability and tight tolerances.

The construction is relative complicated and requires expensive shape-specific tooling.  Due to its high initial investment and tooling cost, it is applicable only for OEMs who need very high-volume production.

Press-assisted bending

The press-assisted system gives high output, good repeatability and tight tolerances, which makes it suitable for long-series OEM production. This bending process combines the benefits of both gravity bending and press bending. When combined with a gravity-based system, the furnace can be used either as a gravity bender or press bender. This makes it the perfect tool for medium-scale operations requiring operational flexibility and long-series OEM windshield production.

600450 Bending as a key factor in windshield manufacturing
Date: 5 May 2015

Others also read

Glaston presents the next chapter in the glass heat treatment business at this year’s GlassBuild America by combining its technology leadership with smart connectivity.
Glaston’s employer-employee (YT) consultation on possible lay-offs and personnel reductions, which was launched in Finland on 9 August 2016, has ended.
At Glasstec, Glaston demonstrates the performance of the all-new flat tempering lines as well as the advantages of Glaston Insight.
At Glasstec 2016, Glaston’s will introduce its latest innovations to help glass processors reach an even higher level of performance.
“It’s really something when you have a new section installed in between all the old, and everything works seamlessly both mechanically and electrically,” says Lone Kjaer Joergensen, Production Manager of Glaseksperten A/S in Hjorring, Denmark.
We’re happy to present the next chapter in the glass heat treatment business at this year’s Glasstec 2016 by combining our technology leadership with smart connectivity.

From industry

Add new comment