3-D Printing Breaks the Glass Barrier

Hot off the presses!  It’s already possible to use tiny granules of glass in a powder bed with conventional 3-D printing techniques like jetting and sintering, but the products turn out opaque. Now researchers at MIT have demonstrated the first-ever machine that can print molten glass through a nozzle and make transparent glass objects layer by layer according to digital instructions.

The most challenging aspect of printing glass is that it must happen at extremely high temperatures. To flow well enough to be extruded through a nozzle, the material must be kept at a temperature greater than 1000 °C.

To achieve this, the printer needs separate heating systems for each stage of the manufacturing process. The molten glass ink is housed in a crucible above the nozzle, where heating coils maintain the desired temperature. The glass flows from the crucible into a custom nozzle, where separate heating coils keep it hot enough to flow and without sticking to the inside. Finally, objects are built inside a third heating chamber, which is kept just above the temperature at which the glass turns solid. This allows the printed objects to be cooled in a gradual, controlled way so that they don’t break.

> Read more detail and view additional video from Mike Orcutt, Technology Review, September 3, 2015