US group develops 3D-printing technique for optical glass

01 Sep 2015

MIT labs and Harvard institute collaborate to enable "creative freedom and bespoke production" of optical glass pieces.

A new system that can 3D print optically transparent glass, known as G3DP, has been developed by a collaboration between the Mediated Matter group at MIT’s Media Lab, the institute’s Mechanical Engineering Department, the MIT Glass Lab and Harvard University’s Wyss Institute. The work of the team led by Professor Neri Oxman is described in 3D Printing and Additive Manufacturing.

 The new platform is based on a dual heated chamber concept. The upper chamber acts as a so-called Kiln Cartridge while the lower chamber serves to anneal the developed structures. The Kiln Cartridge operates at approximately 1900°F (1000°C) and can contain sufficient material to build a single glass architectural component. The molten material gets funneled through an alumina-zircon-silica nozzle.  The project synthesizes modern technologies, with “age-old” established glass tools and technologies, but it can produce novel glass structures with numerous potential applications, the researchers say.

The 3D Printing and Additive Manufacturing article describes the material extrusion printer for optically transparent glass thus: “The printer comprises scalable modular elements, able to operate at the high temperatures required to process glass from a molten state to an annealed product. Processing parameters such as temperature, which control glass viscosity, and flow rate, layer height and feed rate, can be adjusted to tailor printing to the desired component, its shape and its properties, as described by CAD models.

”We explored, defined and hard-coded geometric constraints and coiling patterns as well as the integration of various colors into the controllable process, contributing to a new design and manufacturing space. Printed [glass] parts demonstrate strong adhesion between layers and satisfying optical clarity.”

Production of glass parts is said to be highly repeatable, while the glass constructs resemble those that are conventionally obtained: “the 3D printed glass objects can thus be extended to implementations across scales and functional domains including product and architectural design.” The MIT and Harvard group says its research lies at the intersection of design, engineering, science and art, and represents a highly interdisciplinary approach.

Substantial strength

Professor Oxman's team concludes, “Preliminary printed material characterization was performed in terms of morphological, mechanical and optical properties. Results indicated strong adhesion between layers and substantial strength increase when the process was performed in a heated build chamber with roughly 60% of material strength across layers. From an optical point of view, high transparency is observed and complex caustic patterns have been created with LED light sources, depending on the samples’ geometry.

Commenting on the opportunity presented by their development, the system developers noted, “Two trends in additive manufacturing highlight the value we expect from additive manufacturing of molten glass. First, the freedom that this process provides in terms of the forms that can be created in glass. This enables the creation of structures characterized by higher structural and environmental performance delivered through geometric complexity. Currently we are observing how geometrical complexity can be leveraged for engineering gain, particularly in the aerospace industry in some cases improving performance by 40% or more.

"Second, bespoke creation of glass objects provides the opportunity for complex scaffolds, fluidics and labware custom made for individual applications. Moving forward, the simultaneous development of the printer and the design of the printed glass objects will yield both a higher performance system and increasingly complex novel objects."

About G3DP

The G3DP project was created in collaboration between the Mediated Matter group at the MIT Media Lab, the Mechanical Engineering Department, the MIT Glass Lab and the Wyss Institute. Researchers include : John Klein, Michael Stern, Markus Kayser, Chikara Inamura, Giorgia Franchin, Shreya Dave, James Weaver, Peter Houk and Prof. Neri Oxman. 

A selection of 3D printed glass pieces produced by this method will be presented in an exhibition at Cooper Hewitt, Smithsonian Design Museum, in New York, NY, US, in 2016. The patent Additive Manufacturing of Optically Transparent Glass was filed in April, 2014.

About the Author

Matthew Peach is a contributing editor to optics.org.