A new method of 3D printing could make it possible to create materials up to 100 times faster than is currently possible.
A team of researchers at the University of Michigan (UM) has developed the new method, which lifts complex shapes out of a vat of liquid—much like the T-1000 in Terminator 2—rather than building up plastic filaments one layer at a time.
The researchers’ method uses two lights to control where a liquid resin hardens: a photoactivator hardens the resin wherever one light shines, and a photoinhibitor prevents the resin from hardening.
This allows the team to solidify the resin in sophisticated patterns—creating a 3D bas-relief in a single print run rather than in a series of 2D cross-sections. So far, the team has used the process to print a lattice, a toy boat and a block “M” logo of their university.
This kind of printing first needed to overcome a significant problem, though: the resin tends to solidify on the window that the light shines through, gumming up the print job right at the start of the process. An earlier solution used a semipermeable window that let oxygen through, creating a “dead zone” micrometers thick where the resin didn’t solidify. However, this required the resin to be runny enough that it could flow quickly through the dead zone—resulting in printed materials that needed to be treated gently, such as dental devices and shoe insoles.
The UM team developed a different solution: using a second light that operates on a different wavelength to halt solidification. As a result, the gap between the window and the hardened resin can be much bigger, allowing the resin to flow thousands of times faster. This larger gap also means that thicker resins—which could incorporate strengthening powder additives—can be used to produce stronger objects.
This could be a game changer for large-scale print jobs. It could be more affordable by eliminating the need for an expensive mold that can cost over $10,000. And it could produce items much faster than conventional 3D printing, which builds 3D objects out of a series of 2D layers. In addition, this method also creates stronger materials than filament 3D printing, since those objects can be weak at the interfaces between layers.
“Using conventional approaches, that’s not really attainable unless you have hundreds of machines,” said Timothy Scott, associate professor of chemical engineering, who co-led the development of the new printing approach with engineering professor Mark Burns.
The team is confident that its new printing method will be a commercial success. UM has filed three patent applications, and Scott is preparing to create a startup company that will bring this innovation to the market. “It’s one of the first true 3D printers ever made,” said Burns.
Want to find out more about developments in 3D printing? Check out Bringing Engineered Materials to Additive Manufacturing.