Multiplexing extrusion system development for increased throughput, flow accuracy and improved microstructure

As additive manufacturing technologies advance and 3D-printers get larger, there is a constant need for larger extruders with higher throughput to quickly construct objects. Extruders can continually be made larger, but the weight of an extruder grows faster than its output, and larger/heavier extruders require a stiffer and more expensive gantries or robots to carry and control them. These extruders also struggle with unreliable flow below approximately 10% of their maximum flowrate, causing control issues for small builds and low speed printing operations. The solution we propose to this problem is to use multiple smaller extruders together to achieve the same high throughput of a single large extruder by combining, or multiplexing, the output into a single stream of molten polymer. While multiplexing helps improve the throughput without causing huge weight penalties, the use of smaller and less expensive extruders allows for easier flow rate control on small prints. If the desired print is too small, one extruder can be turned off so that only one extruder is being used for output. This can be extended to more than two extrusion systems, as well. Furthermore, multiplexing can enable the use of multiple materials at once, by using each extruder for a different material. While this leads to extrusion of two or more different materials next to each other side by side, with the modification of the nozzle design and/or multiplexing system we are expecting to enable much more complicated bead designs such as “ribbon” and “core & sheath” and microstructure control. In our initial work, we were successfully able to double the throughput using two identical extruders running at a range of extrusion speeds. We have also showed dual material extrusion in the same bead and we are working on further development of the technology, which we believe will disrupt the AM technology opening new opportunities and applications areas.