Aug. 26, 2022 – Researchers from the Hebrew University of Jerusalem have developed a new wood 3D printing material that can morph into pre-designed shapes.
The eco-friendly raw material, made from a mixture of wood flour and plant extracts, is capable of deformation due to the direction of the fibers in its wood composition that causes it to twist when it dries. Although the team developed the material several years ago, they recently discovered that by controlling how the material is laid down, they can calculate the evaporation of its moisture content, which allows it to form complex objects.
So far, the scientists have 3D printed their wood ink into saddle-shaped, domed, and spiral models, but with further development, the ink material could also be used to create more complex self-assembled objects, such as household furniture.
The unique deformation potential of wood
It is well known that in nature certain species of plants and animals can change shape, appearance, or even texture. When it comes to wood, this ability comes from the orientation of its fibers, which causes it to shrink and warp unevenly, as seen in felled trees. However, warpage may be seen as a problem to be dealt with in 3D printing, but the team is now dealing with it differently.
Doron Kam, a graduate student who recently presented a materials breakthrough at the Hebrew University of Jerusalem at a meeting of the American Chemical Society (ACS), explained, “Warpage can be an obstacle, but we think we can try to understand the phenomenon and exploit it as a desirable deformation.” While artificial structures generally cannot change shape on their own, scientists have increasingly investigated the potential of materials that can deform when triggered by heat, pH, or moisture stimuli. The Israel-based team claims that research in the field has typically been limited to 3D printing flat sheets from gels and elastomers, materials that are synthetic.
The future of 3D printing rivals IKEA?
To take advantage of the natural deformability of wood, the researchers have now integrated it into a material composed of water as well as cellulose nanocrystals and xylan, a natural binder derived from plants. The team has found that the behavior of this raw material can be precisely controlled by adjusting the speed and print path of the nozzle used to deposit it.
Specifically, the study found that any shrinkage is perpendicular to the wood fibers in the ink and that adjusting its deposition speed changes the alignment of these fibers. Thus, accelerating the printing process causes the wood ink material to warp predictably, while slow deposition causes its woody components to become randomly oriented and shrink in all directions.
During testing, it has been demonstrated that it is possible to stack two rectangular layers of raw material into spirals with different orientations while adjusting their warpage to control the direction of their spirals. In addition, the team anticipates that their material could be used for 3D printed furniture projects, such as printing chairs in flat packs that are then turned into products ordered by customers when they open.
In the short term, Israel’s Science, Technology and Space Program department will focus on developing the potential to make the material deformation process reversible. In this work, researchers will develop a method that allows their material to respond to environmental factors, such as humidity, that can eventually be used to return it to its original form.
Advancing the feasibility of 3D printing of wood
While the Israeli team’s deformation findings are undoubtedly innovative, their results are still some way off from actually being put to use. In a similar case, in March 2021, MIT developed a lab-grown 3D printable wood material that is predicted to be deployed in the manufacture of environmentally friendly furniture.
Similarly, an eco-friendly wood 3D printing material was launched a few months ago at the University of Freiburg that has already shown potential for use in construction or light industrial applications. The team’s biosynthetic polymer consists of lignin mixed with cellulose spheres and is said to be compatible with direct ink writing (DIW) and fused deposition molding (FDM) 3D printers.
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