A new research paper describes a way to 3D print soluble supports with resin.
This is a fundamental development in resin 3D printing, and could change how functional assemblies are produced.
Today’s resin 3D printing is always monomaterial: there’s only one resin in the vat, and objects are made from that material. This means that any support structures required must be made from the same resin. Those support structures strongly bond to the object and must be physically removed and discarded.
The support structures typically mess up the surface quality of the object at the point of contact, often requiring additional finishing work to smooth out the bumps.
Resin 3D printer operators accept this process and have routinely performed it for many years. But now that could change.
The paper, entitled ”Dual-Wavelength Vat Photopolymerization With Dissolvable, Recyclable Support Structures”, shows a method of printing in two different materials in a single resin print job. The new process is selective solubility vat photopolymerization, or “SSVP”. Their approach is ingenious, and it’s all about the resin.
They developed a new “two-phase” resin that, like all current 3D printer resins, cures when exposed to a certain frequency of UV light. However, the resin is unique in that it can also cure when exposed to visible light — and when doing so it cures into a different material.
That other material is soluble. It can easily dissolve when exposed to several common solutions, such as baby oil. These solutions can be food safe, suggesting a wider range of possible applications.
Amazingly, one of the solutions in which the visible light-cured structures can dissolve is the original resin itself! In other words, when the print completes it could be dipped in the same resin tank and the support structures would dissolve back into the vat, where they could be reused on the next print.
Automatic support removal AND waste reuse!
Dissolving the support structures apparently takes less than one hour, according to their charts.
The researchers were able to print functional assemblies of components, something that is near impossible on today’s monomaterial resin 3D printers. This brings resin 3D printers to the same assembly capability as dual-extrusion FFF devices using soluble supports.
One big question is whether the objects produced by this process are sufficiently strong to be used as functional objects. I’ve seen what might seem to be terrific new 3D printing processes in the past, but only to find they produce fragile parts. Is that the case here?
It turns out no, the parts are actually quite strong. The UV-cured regions can be strengthened through a post-printing heat treatment. Samples right off the printer exhibited a modulus of 1.1 GPa, but were lifted to 2.5 GPa after heating. This is within the range of typical functional 3D print materials.
SSVP is a very significant development for resin 3D printing. It appears that the hardware required to implement SSVP is relatively straightforward, and the other elements, such as dissolving vats and heating chambers, are easily obtained.
The ability to produce soluble supports doesn’t just make printing an object easier; it also opens up a wide range of operational possibilities. For example, at the top you can see Volumetric Packing. This is an approach currently done only in powder-based 3D printing processes such as SLS.
SLS jobs are usually set up to print a full build chamber of parts, all packed together like a winning Tetris game. That maximizes the throughput of the machine and minimizes operational effort. Previously, this was impossible on resin 3D printers, but now it is possible. It is not possible on FFF devices.
It is highly likely SSVP will be commercialized in the near future, and the world of resin 3D printing will never be the same. This could be the most important development in 3D printing in many years.
Via Advanced Materials and MIT
