A research team from the University of Michigan is attracting attention since it announced the development of a resin-based 3D printing technology that is reportedly capable of achieving print rates up to 100 times faster than conventional 3D printing processes.
Rather than print in a layer-by-layer fashion, the technique uses two lights to control where resin hardens and where it remains fluid, enabling complexly structured objects to be built up in a “single shot” instead of in 2D cross-sections.
It is not only the two-light method that makes the process unique, it is also the resins used by the researchers. That is, rather than use resins that are developed to have one reaction (photoactivation), the resins employed by the University of Michigan researchers include a photoactivator as well as a photoinhibitor, which enables them to harden when exposed to a particular kind of light and remain fluid when exposed to another.
The patent-pending technique also offers a way to print that is not reliant on exposing resin to a solidifying light layer by layer. Instead, the two lights used can be patterned in such a way that the resin can be hardened at nearly “any 3D place near the illumination window.” This could mean dramatically faster print speeds and meeting production demands that are presently out of reach for most AM processes.
“Using conventional approaches, that’s not really attainable unless you have hundreds of machines,” explained Timothy Scott, the U-M associate professor of chemical engineering who co-led the development of the new 3D printing technique in partnership with Mark Burns, the T.C. Chang Professor of Engineering.
Burns, a professor of chemical engineering and biomedical engineering, added: “It’s one of the first true 3D printers ever made.”
As the study’s abstract reads: “We demonstrate a novel method for rapid and continuous stereolithographic additive manufacturing by using two-color irradiation of (meth)acrylate resin formulations containing complementary photoinitiator and photoinhibitor species. In this approach, photopatterned polymerization inhibition volumes generated by irradiation at one wavelength spatially confine the region photopolymerized by a second concurrent irradiation wavelength. Moreover, the inhibition volumes created using this method enable localized control of the polymerized region thickness to effect single-exposure, topographical patterning.”
The 3D printing technique was devised in order to overcome certain challenges associated with resin-based 3D printing. For instance, resin tends to solidify on the window that the light shines through, which inhibits the print process. By creating a large area (some millimeters in thickness) where no solidification happens, the researchers have found a solution to this particular problem.
Further, this could make it possible to work with thicker resins—including those reinforced with powder additives—resulting in more durable parts. Compared to filament-based printing, the method proposed by the University of Michigan researchers offers strength benefits, as parts are not subjected to weak points between layers.
A study detailing the innovative 3D printing technique was recently published in the journal Science Advances. Presently, three patent applications for the technology have been filed and researcher Timothy Scott is preparing to launch a startup company to commercialize the process.