3D printer shown to work ten times faster than other models
A desktop 3D printer that performs up to 10 times the speed of existing commercial counterparts has been developed by engineers at the Massachusetts Institute of Technology (MIT).
The key to the team’s design lies in the printer’s compact printhead, which incorporates two new, speed-enhancing components: a screw mechanism that feeds polymer material through a nozzle at high force; and a laser, built into the printhead, that rapidly heats and melts the material, enabling it to flow faster through the nozzle.
The design was demonstrated by printing various detailed handheld 3D objects, including small spectacle frames, a bevel gear, and a miniature replica of the MIT dome—each, from start to finish, within several minutes.
Anastasios John Hart, associate professor of mechanical engineering at MIT, says the machine demonstrates the potential for 3D printing to become a more viable production technique.
“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,” he said.
“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.”
Hart said he envisions “applications in emergency medicine, and for a variety of needs in remote locations. Fast 3D printing creates valuable new ways of working and enables new market opportunities.”
Commercial desktop extrusion 3D printers currently print at a rate of about 20 cubic centimetres per hour on average, or several Lego bricks’ worth of structures.
The team identified three factors limiting a printer’s speed: how fast a printer can move its printhead, how much force a printhead can apply to a material to push it through the nozzle, and how quickly the printhead can transfer heat to melt a material and make it flow.
“Then, given our understanding of what limits those three variables, we asked how do we design a new printer ourselves that can improve all three in one system,” Hart said. “And now we’ve built it, and it works quite well.”
In most desktop 3D printers, plastic is fed through a nozzle via a ‘pinch-wheel’ mechanism, in which two small wheels within the printhead rotate and push the plastic, or filament, forward.
This works well at relatively slow speeds, but if more force were applied to speed up the process, at a certain point the wheels would lose their grip on the material, which limits how fast the printhead can push material through.
The new model does away with the pinch-wheel design, replacing it with a screw mechanism that turns within the printhead. The team fed a textured plastic filament onto the screw, and as the screw turned, it gripped onto the filament’s textured surface and was able to feed the filament through the nozzle at higher forces and speeds.
“Using this screw mechanism, we have a lot more contact area with the threaded texture on the filament,” Hart said. “Therefore we can get a much higher driving force, easily 10 times greater force.”
The team added a laser downstream of the screw mechanism, which heats and melts the filament before it passes through the nozzle. In this way, the plastic is more quickly and thoroughly melted, compared with conventional 3D printers, which use conduction to heat the walls of the nozzle to melt the extruding plastic.
Hart found that, by adjusting the laser’s power and turning it quickly on and off, they could control the amount of heat delivered to the plastic. Both the laser and the screw mechanism were integrated into a compact, custom-built printhead about the size of a computer mouse.
Finally, they devised a high-speed gantry mechanism—an H-shaped frame powered by two motors, connected to a motion stage that holds the printhead. 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.
“We designed the printhead to have high force, high heating capacity, and the ability to be moved quickly by the printer, faster than existing desktop printers are able to,” Hart said. “All three factors enable the printer to be up to 10 times faster than the commercial printers that we benchmarked.”