Advances in 3D printing have made it easier for designers and engineers to customize projects, create physical prototypes at different scales, and produce restrictions that cannot be achieved with more traditional manufacturing techniques.
However, the technology still has some limitations, such as speed and only being able to use one material at a time.
Researchers from Stanford University have developed a 3D printing method that the team says will create prints faster, using multiple types of resin in a single object. The researchers say the design is five to ten times faster than the fastest high-resolution printing method currently available, and could potentially allow researchers to use thicker resins with better mechanical and electrical properties.
“This new technology will help realize the full potential of 3D printing,” said Joseph DeSimone, Sanjiv Sam Gambhir Professor of Translational Medicine and Stanford Professor of Radiology and Chemical Engineering and corresponding author of the paper. “This will allow us to print much faster, which will help usher in a new era of digital manufacturing, as well as enabling complex, multi-material objects to be manufactured in one step.”
In 2015, a team that included DeSimone created a 3D printing method called Continuous Liquid Interface Production, or CLIP. This method features a rising platform gently pulling the seemingly fully formed object out from a thin pool of resin. The resin on the surface is hardened into the correct shape by a sequence of UV images projected across the pool, while a layer of oxygen prevents hardening at the bottom of the pool and creates a “dead zone” where the resin remains in liquid form. This process was marketed by Carbonwhich, led in the early years by DeSimone, has become one of the big names in additive manufacturing, with in particular Adidas, Riddell and Ford apply technology.
Researchers in the new project say the new design improves on the method Carbon brought to market in 2015.
Deadband is the key to CLIP’s speed. As the solid part rises, the liquid resin is supposed to fill in behind it, allowing for continuous, smooth printing. Problems can arise if the part rises too quickly or if the resin is particularly viscous. The new method is called CLIP injection, or iCLIP, where researchers mounted syringe pumps above the rising platform to add additional resin at key points.
“Resin flow is a very passive process, you just pull the object upwards and hope that the suction can get the material where it’s needed,” said Gabriel Lipkowitz, a mechanical engineering graduate student at Stanford. and lead author of the paper. “With this new technology, we are actively injecting resin into areas of the printer that need it.”
By separately injecting additional resin, iCLIP provides the ability to print with multiple resin types during the printing process, with each new resin requiring its own syringe. The researchers tested the printer with three different syringes, each filled with a resin dyed a different color.
Models of famous buildings of several countries in the color of each country’s flag have been successfully printed. This included St. Sophia’s Cathedral in Ukrainian blue and yellow and Independence Hall in American red, white and blue.
Lipkowitz added, “Applications range from highly efficient energy-absorbing structures to objects with different optical properties and advanced sensors.”
“A designer shouldn’t have to understand fluid dynamics to print an object extremely quickly,” Lipkowitz said. “We’re trying to build efficient software that can take a part a designer wants to print and automatically generate not only the delivery network, but also determine flow rates to deliver different resins to achieve a multi-material goal.”
In 2017, 3D printing played a key role in malaria testing at Stanford University, when researchers produced a very inexpensive centrifuge.
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