Multi-Material Extrusion Based Additive Manufacturing of Flexible Polymetric Materials

Abstract

Direct ink writing (DIW) is a 3D printing technique, capable of printing many different polymers that cannot be 3D printed using other methods. Previous DIW attempts at the University of Oklahoma using a modified Ender 3 printer, to pneumatically print material, focused on printing a carbon nanotube mixture into a silicon resin print bath. Attempts to replicate this process proved successful while simultaneously increasing familiarization with the process. Using direct ink writing material extrusion, a two-material circular nozzle designed to print multiple materials simultaneously was designed, analyzed, and tested at the University of Oklahoma. Additionally, conceptual designs for other nozzles to print from two to five materials at once were also created. A Photon Mono M5s resin printer could create the desired geometry of the nozzle. Provided that the filament utilized was capable of being 3D printed, with a high enough viscosity and shear-thinning properties, the nozzle could create complex two-dimensional geometry. This complex geometry utilized print times of almost 10 minutes with no adjustments to printing pressure necessary mid-print. Additionally, material extrusion could be stopped and restarted with no issues. Future efforts could serve to test out the mechanical properties of pneumatically extruded materials in comparison to the material properties, while also creating three-dimensional geometry or testing different materials in each side of the nozzle.