High throughput 3D printer

Northwestern University researchers have developed a 3D printer that is so big and so fast it can print an object the size of an adult human in just a couple of hours.

The high-area rapid printing (HARP) technology enables a record-breaking throughput for manufacturing products on demand, with both the resolution and throughput of traditional manufacturing techniques.

The prototype HARP is 13ft tall with a 2.5ft² print bed and can print about half a yard an hour – either a single, large part or many small, different parts at once.

“3D printing is conceptually powerful but has been limited practically,” says Northwestern’s Chad A. Mirkin, who led the product’s development. “If we could print fast without limitations on materials and size, we could revolutionize manufacturing. HARP is poised to do that.” Mirkin is the George B. Rathmann Professor of Chemistry in Northwestern’s Weinberg College of Arts and Sciences and director of the International Institute of Nanotechnology. 

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HARP uses a patent-pending version of stereolithography, prints vertically, and uses projected ultraviolet (UV) light to cure the liquid resins into hardened plastic. This process can print pieces that are hard, elastic, or ceramic.

A major limiting factor for current 3D printers is heat. The Northwestern technology bypasses this problem with a nonstick liquid that behaves like liquid Teflon. HARP projects light through a window to solidify resin on top of a vertically moving plate. The liquid Teflon flows over the window to remove heat and then circulates it through a cooling unit.

Although 3D printing is transitioning from prototyping to manufacturing, current 3D printers’ size and speed have limited them to small-batch production. HARP is the first printer that can handle large batches and large parts in addition to small parts.

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“When you can print fast and large, it can really change the way we think about manufacturing,” Mirkin notes. “With HARP, you can build anything you want without molds and without a warehouse full of parts. You can print anything you can imagine on-demand.”

While other print technologies have slowed down or reduced their resolution to go big, HARP does not make such concessions.

Printers on the scale of HARP often produce parts that must be sanded or machined down to their final geometry. This adds a large labor cost to the production process. HARP is in a class of 3D printers that uses high-resolution light-patterning to achieve ready-to-use parts without extensive post-processing.

Mirkin predicts that HARP will be available commercially in the next 18 months.