Researchers at The Hebrew University of Jerusalem developed a method to 3D print flat wooden object that can self-morph into complex 3D shapes.

Traditionally, wooden objects are made by sawing, carving, bending or pressing. Whichever the case, generally material is removed rather than added to create the desired shape.

Inspiration for the research came from wood’s own shrinkage and morphing once a tree is cut down. The researchers aimed to try to understand this phenomenon and use it to their advantage.

The objects are printed using an ink made of wood waste microparticles, also known as wood flour, mixed with natural binders extracted from plants. The way the ink is laid down dictates the morphing behaviour as the moisture content evaporates from the object. For instance, a flat disk printed as a series of concentric circles dries and shrinks to form a saddle-like structure, and a disk printed as a series of rays emanating from a central point turns into a dome or cone-like structure.

The ultimate shape of the object can also be controlled by adjusting print speed, the team found. That’s because shrinkage occurs perpendicular to the wood fibres in the ink, and print speed changes the degree of alignment of those fibres. A slower rate leaves the particles more randomly oriented, so shrinkage occurs in all directions. Faster printing aligns the fibers with one another, so shrinkage is more directional.

The researchers found how to programme the printing pathway, speed and stacking to control the specific direction of shape change, such as whether rectangles twist into a helix that spirals clockwise or counterclockwise. Ultimately, they hope this process can be used to print flat-pack furniture or other wooden products that morph into shape on location.

Photos: Doron Kam / The Hebrew University of Jerusalem