The technique, developed at the Fraunhofer Institute for Mechanics of Materials IWM, directs a laser beam over glass placed in an oven which is pre-heated to just below the temperature at which glass begins to melt.
The glass softens at the points heated by the laser and gravity bends the material into the desired shape. Once the desired form has been achieved, the laser is switched off and the glass solidifies. The result is a shape with bends featuring small radii, waves and round protrusions.
At the back end of the process geometrical data is used to define the sequence of where, when and for how long the material will be heated, as well as to create the program that will control the laser beam. According to Fraunhofer, this factors in options to have the laser momentarily stop, heat a single point multiple times or change the intensity of the beam.
“Thanks to our technique, manufacturers have a cost-effective way of producing extremely customised glass objects in small batches or even as one-offs,” said Fraunhofer IWM scientist Tobias Rist.
From placing the glass in the oven to cooling it off, the whole process takes approximately half an hour. Depending on the shape required, it takes only a few minutes for the laser to do its job.
“A distinct benefit for manufacturers is that the machine is only occupied for short times,” said Rist. “The workpiece is placed in the preheated oven and lasering can begin after just a few minutes.”
Since the glass is removed for cooling, the bending oven is then free for the next workpiece and doesn't have to be cooled down.
Fraunhofer IWM’s Machining Processes, Glass Forming Group used static a CO2 laser with the beam directed via adjustable mirrors fitted to the interior of the oven to provide a fast and simple way of positioning the beam.
The group’s researchers are currently able to process sheet glass with edges of up to 100cm and alter the shape of both sides of the glass.
The researchers’ next step is to experiment with different types of glass and explore further manufacturing variations with a view to expanding the range of shapes products can take.