Researchers at Northwestern University’s McCormick School of Engineering have developed a novel resin-based 3D printer that packs an extraordinary print speed and excellent part precision.
In a display of uniqueness, the system combines photopolymerization with a six-axis robotic arm you might see employed by an industrial DED 3D printer or conventional assembly line. By providing the freedom to move, rotate, and rescale each layer as it is being built, the machine also grants a whole new level of design freedom.
Cheng Sun, associate professor of mechanical engineering at Northwestern University and lead author of the project, states, “The 3D printing process is no longer a way to merely make a replica of the designed model. Now we have a dynamic process that uses light to assemble all the layers but with a high degree of freedom to move each layer along the way.”
A new take on model slicing
When working with traditional planar 3D printers, the software used to prepare models works by slicing an object into flat horizontal layers. As such, these layers can be stacked on top of each other to replicate the STL file in the real world. The Northwestern approach flips this on its head and substitutes the sequential layered approach for a more fluid continuous process.
As the robotic arm of the printer isn’t locked into exclusively building in the Z-axis, it can be used to dynamically transform each layer on the fly, pivoting the printing direction without having to stop or restart the print. Additionally, since the printing engine is a DLP-based light projector, the system as a whole lends itself to rapid curing times and high-resolution features. Entire layers are 3D printed in one go, and there’s no delay between slices so the system operates on an ongoing rolling basis.
Sun adds, “We are using light to do the manufacturing. Shining light on the liquid polymer causes it to crosslink, or polymerize, converting the liquid to a solid. This contributes to the speed and precision of our 3D printing process — two major challenges that conventional 3D printing is facing.”
2,000 layers a minute
Looking at the numbers, the continuous process is capable of printing the equivalent of around 2,000 layers every minute. The researchers demonstrated the system’s power by fabricating a number of test prints, including an Eiffel Tower, a double helix, and a highly-custom vascular stent. Seeing as the 3D printer is also compatible with multi-material builds, the team was able to manufacture a soft pneumatic gripper with a rigid base and soft actuating limbs, paving the way for a new method of rapid part production.
Sun concludes, “This is a very fast process, and there is no interruption between layers. We hope the manufacturing industry will find benefit in it. The general printing method is compatible with a wide range of materials.”
Further details of the 3D printer can be found in the paper titled ‘Conformal Geometry and Multimaterial Additive Manufacturing through Freeform Transformation of Building Layers’. It is co-authored by Cheng Sun et al.
The development of high-speed 3D printing systems is not limited to the experimental confines of a research laboratory. Commercializing its own powerful DLP hardware, optical system manufacturer In-Vision recently launched its most powerful 3D printing light engine to date. Developed over the course of two years, HELIOS is a UV light projector designed specifically for resin-based 3D printing systems, and aims to achieve the highest illumination intensity in the market space.
Elsewhere, 3D printer OEM UpNano has previously upgraded its two-photon polymerization system with high-power lasers to improve its print speeds. The laser, combined with the company’s patented adaptive resolution technology, enabled the firm’s NanoOne printing system to produce highly precise parts with nanoscale resolutions.
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Featured image shows a dynamically morphed Eiffel Tower printed on the Northwestern 3D printer. Photo via Northwestern University.
