3D printing has proven to be one of the most exciting innovations in recent years, evolving from a simple sequential deposition with conventional inkjet to more sophisticated techniques capable of using a vast array of materials. Even glass.
Although glass – with its intrinsic properties of hardness, optical qualities, affordability and availability – does lend itself to many applications, researchers have found its high melting point to be a stumbling block for squeezing it out of printer heads.
Attempts at 3D printing glass have involved two steps: first glass particles (or filaments) are either printed onto a powder bed with a binding agent or they are injected onto a building platform; then a secondary thermal process such as sintering (using heat and/or pressure) is applied. However, these approaches have resulted in opaque, porous glass with suboptimal mechanical properties.
Now, scientists at Massachusetts Institute of Technology have pioneered a 3D printing technique for extruding molten glass. In an exceptionally iterative and methodical process, the researchers created glass objects with varying complexity, examining many parameters and tailoring conditions along the way.
They showed that glass could be heated and injected onto a platform where it cooled and hardened. The shape of the object could be adjusted through precise motion control in the X-Y plane and modification of the platform’s height. Tests showed that temperature regulation was critical at every stage.
Careful heating of glass, as well as continual heating of the feed material and nozzle, were imperative for a consistent viscosity and flow rate. Controlled cooling was also necessary for sticking together layers properly. The finished product, which previously could only have been made using complex casts followed by extensive polishing, was optically transparent, tough and precise, and also demonstrated strong adhesion between layers.
This research describes a single design step that could make manufacturing of bespoke glass objects like complex scaffolds, fluidics used in electronics and lab equipment simpler, quicker and cheaper. It explains how the flexibility of 3D printing could facilitate the scaling up of product sizes to create large, high-performance, complex, geometric structures for the aerospace and automotive industry.
By pushing the boundaries of fabrication methods, 3D printing enables designers to look ahead, assured that the glass is definitely half full.