Volumetric Additive Manufacturing of Glass
Dominique Porcincula | 22-FS-028
Traditional glass manufacturing methods, which typically include melting, molding, and polishing glass, are time and energy intensive and are often done at production scales that do not permit flexibility in fabricating new, novel geometries, thereby limiting innovation in glass optics. Several efforts have sought to change this paradigm by employing additive manufacturing, though these layer-based techniques, including direct ink write and stereolithography, create surface roughness that still requires significant post-processing, such as grinding and polishing. Here, we use the VAM technique, which enables rapid, layerless, single-step fabrication of parts with smooth surfaces, and a UV-curable glass resin to fabricate fully dense glass parts with low surface roughness. This new method for glass manufacturing presents new opportunities for fabricating glass optics, and also opens new opportunities for fabricating optics with novel geometries. In this feasibility study, we aim to adapt a UV-curable silica-laden resin used in glass DIW efforts at LLNL for use in the VAM process. As such, this feasibility study aims to answer the following questions:
- Can we achieve optical quality figure and finish with VAM?
- What surface roughness/smoothness is afforded by printing glass via VAM?
- What are the geometric and dimensional limitations of producing glass via VAM?
We determined that the VAM process is a viable process for producing small glass optics. After correcting for shrinkage, we can achieve surface roughness between 40–100 μm of the model geometry. We have also shown that we can produce green bodies with dimensions of aappro9ximately 1 cm2, with final glass parts experiencing ~50% shrinkage from the original printed green body. A significant effort was made to formulate the glass resin and processing the green bodies to decrease cracks, bubbles, and other defects that may arise during printing and processing.
This feasibility study supports LLNL's Accelerated Materials and Manufacturing and Lasers and Optical Science and Technology core competencies. As a novel manufacturing capability, VAM enables 3D printing of many structures that are difficult or impossible to make even for other AM techniques, let alone conventional manufacturing. Fabrication of glass optics via VAM would create new avenues for optics fabrication at LLNL, including potential optics applications within the National Ignition Facility. Future work in this area also opens up the possibility to incorporate GRIN into VAM printed optics. Development of this technology adds to the portfolio of capabilities needed to meet future national security challenges and enables the NNSA to create new ways of responding to national security challenges. This technology also provides new paths to strengthening domestic optics manufacturing, much of which has moved outside the United States in past decades.