A 4D printed object looks similar to a 3D printed object. However, it can change shape or self-assemble when its environment changes. [Teaching Tech] This technology caught his attention and he decided to make it work with his existing 3D printer.
His attempts to make a joint that changes when submerged in the water looked at several options: material that can absorb water, material that expands with temperature, and — the selected option — a dissolvable locking mechanism. A water-soluble lock holds a hinge open. The hinge can be repositioned if the lock is broken by water.
This experiment was not without its faults, as are most. You always learn something every time. The final design featured a TPU hinge, spring, and PLA structural beams. Flat printing was required for the TPU, so pieces must be able to rotate so that they can be placed in their final orientation.
Usually, multi-material setups are for printing different colors of the same kind of plastic, it’s possible to use different plastics, but it can be tricky. It’s possible to use both plastics and other materials as a compromise. [Teaching Tech] One print was made using PLA and TPU. The PVA locks were printed in separate passes and attached to the print at the end. The first finished 4D print wasn’t entirely successful. Although the hot water slowly disintegrated PVA, it also deformed PLA. It made a huge difference to the lock’s design.
We aren’t sure this is practical yet, but we are sure someone has a need for this technique and it could be made very practical with a little work. There were magnets in 4D printing when we last saw it. We think this is an exciting time where people aren’t just trying to get conventional printing to work well, but are pushing the envelope with new techniques like conical slicing, for example.