Rapid Liquid Print has made some big steps since we last saw them in 2023.
The company has developed a highly unusual 3D printing technique that is able to successfully produce incredibly soft objects.
Their concept is actually quite straightforward: extrude silicone with a long syringe into a tub of hydrogel, which you can see at the top. The hydrogel acts as support material for the soft silicone, and full 3D objects can be easily produced.
This is a very attractive technology because it can produce soft parts that are far more durable than simply using TPU. TPU is a thermoplastic that can soften or melt in higher temperature applications, whereas the silicone used by RLP does not. Evidently, the automotive industry has specific interest in this aspect.
When we last saw RLP, they were only demonstrating the technology. In other words, they had a tub of hydrogel with some pre-printed soft objects. That was impressive on its own, but since then, they’ve packaged the technology into a fully operational 3D printer, the Levity.
The Levity is basically a square tub of hydrogel with the syringe apparatus above. The build volume is said to be 500 x 500 x 500 mm, but the objects would tend to be much smaller, as you can see in these images.
There are some peculiarities about the RLP process. We learned that the printing must be done in a continuous manner, which means that all objects are printed as a single spiral extrusion.
It is possible to “travel” to another spot in the tub and begin another object, but it seems that to ensure proper layer adhesion, the spiral approach is required. Because of that, the company has developed sophisticated software to generate the complex toolpaths required. However, it also means that the Levity cannot print some geometries.
There’s more to the process than just the printing. The silicone material has to cure, and that apparently takes an overnight stay at the workshop. This means that Levity operators should have multiple hydrogel tubs ready to go: pull out a completed tub for curing, and immediately insert a fresh tub for more printing. This is similar to how some powder-based 3D printing processes work, except here there’s no heat involved at all.
The Levity is designed as a production machine and is not intended for prototyping. This is another reason for the ability to swap out hydrogel tubs.
We asked about the hydrogel, and it turns out it is quite reusable. After removing the objects — which is done by simply reaching in and pulling them out — you can immediately use the tank again for another print. The hydrogel slurps back into place and is ready to go.
However, the hydrogel must eventually be renewed. We were told that the tub must be changed out “every couple of weeks”.
It is also possible to print slightly multicolor objects with the Levity, as you can see here. Basically, they switch the color of the silicone during extrusion, much like the layer change colors on FFF 3D printing.
As of today, RLP is providing prints via a service, but they intend on eventually selling the Levity directly to customers.
