Carbon Fiber 3D Printing

A fused deposition modeling (FDM) 3D printer capable of printing a carbon fiber reinforced polymer (CFRP) filament in curved layers was developed by Jackie Song and I for our capstone senior design project (2014-2015). The driving force behind this project was the weak thermoplastic materials and poor adhesion from planar layers that limit most 3D printing to rapid prototyping applications. With stronger filament materials and layer orientation optimized for the loads imparted on a given specimen, load-bearing implementation of 3D printed parts could be realized. With this in mind, we set out to created and utilize a CFRP filament and print using curved layers aligned with loads to take full advantage of a carbon fiber composite filament.

To created the printer, an extruder end-effector was designed and fabricated for mounting to a FANUC LR Mate 200iC industrial robot arm. The extruder uses RepRap 3D printing hardware and is controlled by a Megatronics controller. The FANUC robot provides the six degrees of freedom necessary to realize curved layer 3D printing. The open-source Megatronics microcontroller and FANUC robot system were programmed with toolpaths and extruder speeds for a sample bridge specimen (shown above). A novel ABS-matrix carbon fiber filament was created using dipping methods and a composite finitie element analysis (FEA) using filament material properties was used to predict specimen strength, stiffness, and failure behavior. Filament tensile tests demonstrated stiffness on the same order of magnitude as aluminum while FEA predicted CFRP part stength to be nearly twice that of an ABS analog, and the stiffness to be on the same order of magnitude as an aluminum part. While the project progressed very far, inefficiencies in filament manufacturing ultimately prevented us from printing with CFRP using the FANUC (CFRP extrusion was validated using a 3Doodler) within the academic year.Ā A masters student at Cooper Union will pick up this project for their thesis, intending to finalize an efficient filament manufacturing process, print, and experimentally quantify theĀ strength and stiffness of CFRP 3D printed components compared to their planar layer and curved layer ABS analogs, as well as the FEA predictions.

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