Glass 3D Printing
This week, I’ll be exploring the fairly new world of 3D printing glass. Any Optical engineers’ eyes and heart light up when they can read about advances in 3D printing glass. For centuries, glass fabrication techniques have been largely unchanged, except for industrial equipment modernization. As of now, 2 traditional 3D printing techniques have been relied upon for the development of glass rapid prototyping. SLS (selective laser sintering) and FFF (fused filament fabrication) have been trail-blazers for the future of glass rapid prototyping. But recently, two new methods of 3D printing glass have emerged with great promise. The first, an old face to the 3D printing game, SLA (stereolithography), and the second is an entirely new concept but with a familiar twist, DIW (direct ink writing).
Current Technology Breakdown
First off, there was a clear and defined front runner, which was actively developing glass 3D printing. The Israeli-based, Micron3DP, launched its first glass capable 3D printer prototype in 2015¹. They were not the first company to produce prototype glass printers but quickly became the most noteworthy. Micron3DP relied on an extremely high-temperature version of FFF and primarily soda-lime and borosilicate materials¹. Micron3DP developed their respective processes and devices, for the next two years with virtually no major breakthroughs. However, in 2017, Micron3DP completed the first fully operational, high-resolution glass printer system at their Kfar-Saba facility in Israel¹. Micron3DP eventually came to terms with an external beta testing contract in order to continue the development.
Almost simultaneously in 2015, the Mediated Matter group out of MIT (Massachusetts Institute of Technology) was breaking ground on their own extrusion-based glass printer as well. MIT”s approach was unique in regards to the manner in which the temperatures were controlled in order to dial in print results. They utilized a 3-stage, temperature control printer layout with a hopper-style loading system². Unfortunately, much like Micron3DP, the MIT group stalled out until 2017 when they showcased the 2nd version of their G3DP (glass 3D printer). Although both technologies have promise for further improvements, their main drawbacks are the finished products’ resolution. Ask any optical engineer, glass is the gold standard when it comes to optical design but if you lose resolution during the processing, you’re defeating the purpose of using glass in the first place.
Next Chapter in Glass Printing
Although Micron3DP and the MIT glass lab group have yet to refine their processes into a viable manufacturing solution, 2017 did bring more hope to the table as well. First, the Karlsruhe Institute of Technology out of Germany introduced their SLA version of glass printing². What’s the catch you say? There’s always a catch, the finished prints require a post-process heat treatment of roughly 1300° C to burn off the photopolymer leaving behind a hardened and solid finished glass piece. This special SLA printer utilizes a glass nano-powder “ink” which is compounded with a semi-typical photopolymer².
Next up, two other major universities (University of Minnesota & Oklahoma State University) in collaboration with the LLNL (Lawrence Livermore National Laboratory) were responsible for bringing a newer 3D printing process to the glass game, known as DIW. The group of scientists and researchers involved claim their printed samples are a viable approach to optics grade 3D printed glass³. Much like the SLA glass process created by the German Institute, the LLNL DIW prints need to be post-processed in order to densify and align the micro-structure for maximum clarity. Very similarly, the special “ink” used in the LLNL formula is a silicate-based concentrated suspension with a highly controlled flow process³. The LLNL research group has already claimed the ability to print “transparent” glass samples, but they’re now turning their attention to GRIN (gradient refractive index) optics and micro and nanofluidic device development.
1 – https://ceramics.org/ceramic-tech-today/glass-1/3d-printed-glass-where-are-we-now
2 – https://news.mit.edu/2015/3-d-printing-transparent-glass-0914
3 – https://www.llnl.gov/news/lab-breakthrough-3d-printing-glass