Investigating Foaming Materials in 3D Printing

Abstract

This thesis investigates novel foaming materials for fused deposition modelling (FDM) which have been introduced in 2019. The materials are able to foam by the addition of foaming agents. Foaming materials for FDM printing can be advantageous since they can create lightweight models, and have good impact strength and toughness in relation to their weight (Nofar et al, 2022). The goals of this thesis are to: research the existing knowledge about foaming materials for FDM printing, characterize the different printing parameters that influence the amount of foaming and propose an application for foaming materials for FDM printing. The investigated materials are foaming PLA, ASA, and TPU.
The first goal is reached by conducting a literature review. First, the material properties of foaming materials outside the scope of FDM printing are investigated to better understand the advantages for foaming materials for FDM as well. Second, printing parameters are investigated to understand how these affect final printed products. Third, the available literature for the foaming filaments for FDM printing is investigated. An overview of the material properties in tension is made for the foaming filaments. This shows that most material properties are known for the foaming PLA.
The second goal is reached by conducting three experiments, which investigate the influence of nozzle temperature, fan, printing speed and flow rate. From these experiments it is concluded that the nozzle temperature, printing speed and flow rate influence the expansion of the material, depending on the desired outcome. The fan speed only influences the expansion of the foaming TPU. With the results of these experiments, an overview is made of the influence of the printing parameters on the expansion using the three-link chain model (Doubrovski et al, 2011).
The third goal is reached by conducting a compression experiment in which the foaming PLA is compared with expanded polystyrene (EPS). The results from this experiment and the printing parameters are applied within a motorcycle helmet as demonstrator. This demonstrator shows that the foaming materials for FDM printing could be an interesting area for further research.
This thesis provides a starting point for further research into the influence of printing parameters for foaming materials, as well as the material properties of the foaming filaments. It is recommended to further investigate the influence of more printing parameters on foaming, such as bed temperature, nozzle geometry and type of printer. Second, it is recommended to further investigate the material properties of foaming TPU and ASA as well, since only PLA was tested in the compression experiment. Apart from this, the materials could also be further investigated for tension. Lastly, the proposed foaming PLA sample for the motorcycle helmet could be further investigated for higher strain rates, to confirm the feasibility for the use of motorcycle helmets.
Overall, this thesis investigates the printing parameters for foaming materials which are used to create samples with specific densities for a compression experiment. With the found printing parameters and results from the compression test, a helmet demonstrator is create