These days, 3D printing can be done with a great many different and extraordinary materials. 3D printing of glass is a new challenge because it becomes a treacly liquid when melted and – in the case of thin-walled products – very brittle after solidifying. Therefore accurate temperature control is essential to able to control the printing process. Philips Lighting Winschoten (now taken over by the German company QSIL) asked DEMCON to develop a 2.0 version for systematic process research and the automatic printing of demonstrators with their 3D glass printer.
The printer consists of a printhead in which glass is melted and a platform that makes an x-y-z movement beneath the flow of glass to create the required product. Crucial to the final result is managing the temperature of not only the melting glass in the printhead (1,600 -1,700 ºC) but also the printing platform and ambient atmosphere (low oxygen to prevent corrosion). If the end product cools down too quickly, tension can build up within it. For this reason the platform and atmosphere are set at maximum 700 ºC.
Demcon Kryoz its expertise on thermodynamics is used to equip the system with heaters and coolers that ensure balanced temperature regulation; a pyrometer measures the temperature of the printhead. The nitrogen which is continually blown into the furnace is pre-heated to prevent temperature fluctuations. Due to the high process temperatures, thermal expansion was an important design aspect. Thermal simulations served to underpin the design choices in terms of hardware (materials) and software (possible compensations).
As result the first printer in the world is created that is able to print glass in such a controlled way. I we are proud to contribute in this Demcon project and of the fact that together we have manged to meet the specifications for temperature, mechanical stability and accuracy. All that was achieved even though what we were working on was a prototype, so we couldn’t simply carry on designing and simulating to fix every single issue. Together with our customer QSIL, we managed to strike a good balance.