Self-folding structures from the 3D printer: New technology makes targeted use of internal stresses

3D printing not only enables precise manufacturing, but also innovative material manipulation. A new technique, based on research by the Morphing Matter Lab at UC Berkeley, specifically uses internal stresses in 3D-printed components to fold them into a predefined shape by applying heat. YouTuber CNC Kitchen has tested this method and shows how it works in practice.

In 3D printing, the layer-by-layer application of plastic often creates unwanted stresses that can lead to warping or deformation. However, the researchers discovered that these stresses can be specifically controlled. If the component is heated above the glass transition temperature (Tg), the embedded stresses relax, causing it to automatically fold into a programmed three-dimensional shape.

The technology combines different materials such as PLA (as an active layer) and TPU (as a passive, restrictive layer) to specifically influence the deformation process. Depending on the printing direction and layer structure, different bending or twisting patterns can be created.

YouTuber CNC Kitchen tested the method with various printing parameters. In his experiments, he showed that the printing speed plays a significant role: Higher speeds generate more internal stresses and lead to greater deformation. He also found that Hilbert curve infill is particularly suitable for keeping flat areas stable, while other print patterns can be used specifically for subsequent shape changes.

Another highlight of his tests was the use of a sandwich structure of PLA and TPU, which enabled programmable bending. He also demonstrated that the molded parts could be returned to their original shape by reheating, an effect that could be useful for reusable or adaptive designs.