Cutting Curves in Safety Glass

The safety glass used in vehicle windows sandwiches a tear-proof film between two layers of glass. The system prevents shards from forming if the glass breaks, but the embedded film makes it difficult to cut safety glass in anything other than a straight line.

But researchers at Germany's Fraunhofer Institute for Mechanics of Materials say they have solved the problem with a laser system that vaporizes the film before the glass is cut. The group, working with glass processing equipment supplier Hegla GmbH, are presenting their technology this week at the Glasstec trade fair in Dusseldorf.

Normally, cutting safety glass involves carving and fracturing the panes of glass on either side of the film inside. Then the break line is heated, thus softening the film so it can be stretched by pulling the two halves apart. Finally, a blade inserted between the panes cuts the film. The close tolerances involved make curvy cuts virtually impossible.

The Fraunhofer-Hegla process reverses the sequence by melting the film before the glass that encases it is scored and broken apart. The researchers say their system can be easily automated and scaled up for industrial production. They currently are fine-tuning the patented technology to speed up the process.

The scientists describe the system as operationally ready, and Hegla is using it to develop commercial cutting equipment for laminated glass.