Additive Manufacturing of Glass via Digital Glass Forming

Glass has many unique material properties that make it an attractive material for many consumer and scientific applications. Due to brittle fracture mechanics, smooth crack-free glass cannot be machined by chip-based manufacturing (milling or lathe operations). As such, it is very challenging to manufacture intricate, low production-volume parts without using the services of an artisan glassblower. This presents an opportunity for additive manufacturing technologies to fill this niche to build precise, fully dense glass parts in unique geometries that would be difficult to manufacture by hand. This dissertation focuses on one such technology, digital glass forming. This technique uses a CO₂ laser to locally heat a solid glass feedstock as it is fed into a glass substrate material. This technique has been used previously for fully dense parts but has been limited by slow deposition rates due to thermal diffusion. Reconfiguring the deposition system to heat the interface between filament and substrate directly permits the filament to deform the molten zone and significantly improves deposition rates. Additionally, this advantageous heating condition allows for the deposition of open tube feedstocks. The loading on the laser heated region is controlled by the stages as well as pneumatic pressure inside the tube, which allows printing of complex shapes without the tube collapsing. Additionally, the high molten viscosity of glass allows for the deposited material to be used as supports for subsequent material, allowing for the deposition of free-standing structures without scaffolding or support. Finally, by utilizing single mode optical fiber as a feedstock has allowed for the forming method to be used to deposit optical fiber waveguides. These improvements to deposition mechanics and feedstock selection are necessary for the integrated parts, including optofluidics and photonic sensors.