Design and fabrication of a system for the additive manufacturing of transparent glass

Abstract

Despite glass\u27 prevalence in the scientific and engineering community, very little research has been conducted attempting to additively manufacture (AM) glass. Even less research has been done on optically transparent glass. Glass’ material properties make it ineligible for most AM processes if the end result is to be transparent. Even small gas inclusions can cause large amounts of scattering. Additively manufacturing transparent glass brings the advantages found in other AM processes with the added benefit of having optical properties better than those found in polymers. Additively manufacturing glass also allows the optical properties of transparent parts to vary arbitrarily. This thesis presents the design, manufacture, and control of a system to AM transparent glass. The system feeds glass wires, which are opaque in the near infrared, into a melt pool maintained by a CO₂ laser (10.6μm). The laser beam and melt pool remained fixed as the AM part is moved using a motion stage as the glass is deposited layer-by-layer. The stages are controlled using a PID controller, and the wire feeders are controlled using a PD controller. A spring damper model is also presented to model the deposition process along the feed direction, and perpendicular to the feed direction for control purposes. The Glass AM process is able to create morphologically accurate glass pieces more efficiently, and with fewer filament breakages than the prototype system. The glass produced with this system has optical properties as good as cast glass. The Glass AM system is also expandable and interchangeable so that more subsystems can be added and changed with minimal redesign --Abstract, page iii