(170g) Rotary 3D Printer for Additive Manufacturing of High Viscosity Filled Thermosets

The Aerospace and Defense industry requires tough, high strength complex geometry parts. For the most part, these properties are achieved via fiber reinforced thermoset polymers. Additive manufacturing (AM) techniques allow complex parts to be made more efficiently while keeping production costs low. But current AM technologies, such as DLP and SLA, are restricted to lower viscosity unfilled resins, or technologies, such as DIW, introduce voids during manufacturing which decrease the part’s overall mechanical performance. In this work, we introduce a new 3D printing technique focused on high viscosity filled resin systems that minimize defects during manufacturing such that AM of high-performance polymer parts with complex geometries is realized.

The technique combines the exposure system of a traditional DLP printer with an industrial extrusion process on a rotating build platform. The coating and printing process is continuous. The printer operates by pumping resin onto the circular build plate as it rotates along the Z axis, coating the plate with each layer. A novel slot die nozzle that is designed to apply a constant shear-rate on the extrudate, is used to form a uniform layer of the resin independent of fluid rheology. The DLP then projects a moving pattern onto the moving build platform. Current work includes modeling the layer height deposition on the circular bed and creating a working curve for the printer projection system. We will discuss several challenges of printing on a rotating bed geometry. Our findings have been developed into a slicing methodology that is validated for a wide range of print geometries. 3D profilometry is used to characterize the fluid mechanics and reaction kinetics of the printing method. The results are presented as a function of fluid rheology to determine correlations with part fidelity and quality. Overall this method moves us one step closer to user-end high-performance thermoset parts for on-demand manufacturing.