A new approach to reinforcing 3D-printed components could provide more stable structures in the future. YouTuber JanTec experimented with the technique of “infill injection”, in which cavities inside a printed part are subsequently filled with molten plastic. The method is intended to increase mechanical strength without the need for additional hardware or inserts.
The inspiration came from two similar processes: Z-Pinning, in which vertical channels are reinforced with molten plastic, and VoxelFill, a patented technique from AIM3D that selectively fills non-uniform cavities to better absorb loads in different directions. It is important to emphasize that JanTec conducted its experiments independently and did not infringe any existing patents.
Initial tests showed that molten plastic solidifies quickly in a deep, open cavity and cannot fill the entire length of the channel. To avoid this problem, the cavity was filled gradually and from the bottom up. In addition, a modification to the print head proved helpful: an extended nozzle, obtained from an airbrush nozzle, enabled better material distribution within the cavities. A higher extrusion temperature also improved the filling quality.
The additional heat energy posed a further challenge. Large quantities of molten plastic can deform the surrounding material. By using a higher number of perimeters and a denser infill, the heat absorption of the structure could be improved and deformation minimized.
Tests showed that infill-injected parts had a significantly higher impact strength than conventional prints. The effect on flexural strength was lower, possibly due to the short test geometry. These initial results suggest that the technology is particularly suitable for applications where high impact strength is required.
Further details can be found in his video:
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