Researcher(s)
- Quinlan Kraft, Chemical Engineering, University of Delaware
Faculty Mentor(s)
- Alexandra Bayles, Chemical Engineering, University of Delaware
Abstract
Multi-material additive manufacturing (MMAM) – the layering of different components in a printed material – is the next generation of additive manufacturing process design. This fabrication method can achieve complex spatial hierarchies in a structure, improving material properties such as strength and durability or creating new functionalities altogether. However, one major bottleneck of conventional MMAM systems is throughput. To create fine details in a printed structure, printing nozzles must be small, and the time required to swap inks and purge unwanted materials decreases the efficiency of a relatively slow process. Advective assembly is a novel method that addresses these problems by patterning multiple inks inside a larger printing nozzle, using folding and cutting transformations in complex channels to layer multiple materials simultaneously. However, these complex nozzle geometries make advective assemblers prone to non-ideal dynamics, resulting in potential irregularities in the patterning of printed materials. To assess these trends, rheological measurements were conducted on two model printing inks: NIVEA containing five percent and fifteen percent hexadecane. Each ink was extruded through two different advective assembly nozzles across a range of flow rates. These extrusions were cross-sectioned and converted into binary images, which were compared against the theoretical nozzle pattern. The Jaccard index was used to quantify the similarity of the two structures. It was found that over the range of flow rates and patterns tested, there was no significant change in the Jaccard index over two orders of magnitude of flow rate, though minor visual changes were noted. From these results it is hypothesized that – compared to conventional MMAM methods – advective assembly systems can enable high throughput processing while preserving functionality, but more descriptive analytical methods must be leveraged to fully describe the warping effect observed at heightened conditions.