3D printing system released by MIT
The Massachusetts Institute of Technology (MIT) is, quite simply, improving 3D printing. Anastasios John Hart is an Associate Professor of Mechanical Engineering and Director of MIT’s Laboratory for Manufacturing and Productivity and its Mechanosynthesis Group.
He’s been working with MIT engineers to develop a desktop 3D printer that can perform up to 10 times faster than commercial 3D printers currently on the market. “If I can get a prototype part, maybe a bracket or a gear, in 5 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. If I’m a repair technician and I could have a fast 3-D printer in my vehicle, I could 3D print a repair part on-demand after I figure out what’s broken,” Hart said. “I don’t have to go to a warehouse and take it out of inventory.” Hart and 2015 MIT graduate Jamison Go, a former researcher in Hart’s lab, published the results of their work on developing their FastFFF 3D printing system in a paper, “Fast Desktop-Scale Extrusion Additive Manufacturing,” in the journal Additive Manufacturing.
The two discovered that commercial desktop extrusion 3D printers can only print at an average rate of 20 cubic centimetres an hour, citing three main factors – how fast its printhead moves, how much force the printhead applies to materials to get it through the nozzle, and how fast it transfers heat to melt a material and make it flow. All these factors limited how fast 3D printing could be. Example? While most desktop 3D printers can make a few Lego-sized bricks in an hour, the MIT FastFFF system is able to produce the same amount in just minutes, thanks to its newly designed and compact printhead. Typically, a pinch-wheel mechanism feeds plastic through a 3D printer’s nozzle, then two small wheels inside the printhead rotate to push the filament through, which works fine at slower speeds. However, the wheels will lose their grip if more force is applied to speed up the process. Hart said that this ‘mechanical disadvantage’ is responsible for limiting the speed of most desktop 3D printers.
Hart and Go eliminated the pinch-wheel, and added two new components to its printhead that enhanced the 3D printing’s speed – a screw mechanism that turns inside the printhead, and a laser that’s built into the printhead downstream of the screw mechanism, which rapidly heats and melts the material before it’s fed through the nozzle (so it can flow much faster). While most commercial 3D printers heat the nozzle walls with conduction to melt the plastic, the researchers’ method allows the material to melt more quickly. Also, by turning the laser on and off quickly and adjusting its power, Hart and Go were able to control how much heat was applied to the plastic. To demonstrate their new 3D printer’s capabilities, the researchers fabricated various complex, handheld objects. Each one was 3D printed within five to ten minutes, versus the hour it would have taken on a conventional 3D printer.
“We’re interested in applying this technique to more advanced materials, such as high-strength polymers and composite materials,” Hart added. “We’re also working on larger-scale 3-D printing – not just printing desktop-scale objects, but bigger structures for tooling or even furniture. The capability to print fast opens the door to many exciting opportunities.”
Credits: Graphic Arts