Washington, May 30 : Fraunhofer scientists have come up with a way to cut glass with superior edge quality cost-efficiently.
Lead researcher Dr. Rainer Kubler says that his approach is based on a laser-induced stress separation process that causes minimal damage to flat glass.
He points out that in the conventional process used to cut flat glass, a small cutter wheel scores a line into the glass, and pressure is then applied to the glass along this line so that it breaks.
The researcher says that glass splinters coming off in the process produce defects known as micro-cracks, and the glass consequently needs to be reworked by grinding and polishing, which costs time and money.
Nonetheless, damages may remain in the glass that reduce its strength, he adds.
Kubler says that instead of scoring the glass mechanically, his process is based on applying stress.
"We have to heat the glass along the required separation line without damaging it. We do it with a CO2 laser," says Kubler, who has been awarded the Joseph-von-Fraunhofer Prize 2008 for his work.
He has revealed that the second part of the secret is to shock-cool the glass by means of a cooling nozzle following right behind the laser beam, blowing cold air onto a specific area of the glass.
The researcher says that the temperature difference creates a stress field, which in turn leads to a crack.
Thereafter, says Kubler, the thermal crack introduced into the surface by this process is opened by bending the glase plate until it separates.
He says that extensive experience and numerical simulation have helped manage the process and particularly the crack, to produce the crack in a controlled manner and use it as a tool.
"Our process has enabled us to produce extremely high-quality glass edges. And flawless, smooth edges mean firmer glass," says Kubler.
He adds that the stability of the edges determines the strength of the entire pane, opening up entirely new applications for the use of glass panes in architecture.
According to him, the flawless edges may make it possible to make thinner the installed glass panes, without sacrificing any of their reliability.