Materials

Glass-shaping lasers could replace molds

Glass-shaping lasers could rep...
The technique was used to place the arcing curves in this glass
The technique was used to place the arcing curves in this glass
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The technique was used to place the arcing curves in this glass
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The technique was used to place the arcing curves in this glass

If you want to incorporate protruding three-dimensional features into a flat sheet of glass, the typical way of doing so involves heating that glass up and placing it in a mold. Those molds are costly to manufacture, however, plus the casting process isn't a quick one. That's why Germany's Fraunhofer Institute for Mechanics of Materials has developed a laser-based alternative technique that promises to be cheaper and faster.

The process begins with the unaltered glass sheet being placed face-down over an open space in an oven – that oven has been preheated to just below the melting point of glass.

Once the glass reaches that temperature, a laser beam guided by moving mirrors is used to selectively further heat the parts of it that are intended to protrude. This causes the glass in those areas to soften to a thick-honey-like consistency.

Because the glass sheet is unsupported underneath (except around the edges), gravity causes those softened bits to start sagging down. Once they've reached the desired shape, the laser is switched off, allowing the glass to cool and harden in its new form.

The whole process, from placing the glass in the oven to its being cooled down completely, takes about half an hour. That said, depending on the complexity of the design, the glass only needs to be in the oven and exposed to the laser for a few minutes – it's set to cool outside of the oven. This means that many pieces of glass could be moved through in a relatively short time.

The scientists are now studying how the process works with various varieties of glass, and are experimenting with the types of shapes that can be produced.

Source: Fraunhofer

5 comments
MartinVoelker
I once had the opportunity to ask the director of a Fraunhofer Institute about the difference between Germany's Max-Planck Institutes and Fraunhofer. He said " Max-Planck Institutes turn money into knowledge – Fraunhofer turns knowledge into money!" This process might well be an example of this.
Expanded Viewpoint
Glasses have no "melting point" to them. They just get softer and softer and closer to a liquid state as they are heated up. So what this process really is, is one where the glass is heated up to a certain point where the additional energy from the laser beam then creates the desired effect; the glass being reshaped by the force called gravity acting upon it.
Don Duncan
E.V.: So are you saying heated glass that flows is still a solid? At what point does a solid become a liquid? You seem to imply glass never will liquify, but just approach the liquid state.
DouglasAnkrum
....EV and DD.....there's still the argument that glass is not ever a solid, but a super-cooled liquid...? This statement from recent article here about Prince Ruperts Drops.....
SaysMe
Why does the title state could replace molds? It still uses molds, it is replacing long heating time hense energy and time saving...