3D Printing Gets 10x Speed-Up with Changes to Print Heads

• By Joshua Bolkan
• 11/30/17

Researchers at the Massachusetts Institute of Technology have developed a desktop 3D printer that they say is up to 10 times faster than those currently commercially available.

Anastasios John Hart, associate professor of mechanical engineering and director of MIT's Laboratory for Manufacturing and Productivity and the Mechanosynthesis Group, partnered with Jamison Go, a former graduate researcher in Hart's lab, identified in a previous paper three issues that slow down printer performance.

The first hurdle was the mechanism feeding printer filament to the printing nozzle. Most printers use a pinch-wheel design, or two wheels that turn together to pinch the filament between them and pull it toward the head. The problem with this design is that, when the process is sped up, the wheels lose traction and slip against the filament instead of pulling it.

To move filament faster, the team replaced the pinch wheels with a screw design inside the printhead that turns and pulls a textured strand of filament through as it does so.

"Using this screw mechanism, we have a lot more contact area with the threaded texture on the filament," Hart said in a prepared statement. "Therefore we can get a much higher driving force, easily 10 times greater force."

Another factor limiting printing speed is how fast the filament can be heated. Most commercial desktop printers heat the nozzle on the printhead to in turn heat and melt the filament through conduction.

Hart and Go used a laser that can be quickly turned on and off to control the amount of heat applied to the filament, and thus, how much is melted.

The third problem the team had to overcome was the speed at which the printhead can move. To meet this challenge, the pair designed "an H-shaped frame powered by two motors, connected to a motion stage that holds the printhead," according to an MIT News release. "The gantry was designed and programmed to move nimbly between multiple positions and planes. In this way, the entire printhead was able to move fast enough to keep up with the extruding plastic's faster feeds."

Hart said the speed at which 3D printers operate is a main factor keeping them from wider use.

"If I can get a prototype part, maybe a bracket or a gear, in five to 10 minutes rather than an hour, or a bigger part over my lunch break rather than the next day, I can engineer, build and test faster," said Hart, in an MIT news release. "If I'm a repair technician and I could have a fast 3D printer in my vehicle, I could 3D-print a repair part on-demand after I figure out what's broken. I don't have to go to a warehouse and take it out of inventory."

In the future, the team plans to speed the process up even more through active cooling of the object being printed and mathematical optimization of the path the printhead takes as it works. They also hope to work with new print materials.

"We're interested in applying this technique to more advanced materials, like high strength polymers, composite materials. We are also working on larger-scale 3D printing, not just printing desktop-scale objects but bigger structures for tooling, or even furniture," Hart said in a prepared statement. "The capability to print fast opens the door to many exciting opportunities."

Hart and Go published their most recent work in Additive Manufacturing. The paper is available at sciencedirect.com.