MIT creates high-speed 3D printer
MIT is leading the way in 3D printing technology. Using new 3D hardware and dubbed FastFFF (Fast Fused Filament Fabrication), the newly-developed machine is claimed to be 10 times faster than contemporary 3D printers in use today.
MIT’s associate professor of mechanical engineering and director of the Laboratory for Manufacturing and Productivity and Mechanosynthesis Group, A. John Hart, believes that fabrication of objects in the future could happen in a “matter of minutes”.
The development means complex, mass-produced products, and parts could be created even without part-specific tooling and machines, signaling a future of agile manufacturing that negates the needs for expensive, bespoke machinery.
“3D printing compels us to rethink how we develop, produce and service products,” said Hart.
For the uninitiated, a common method of 3D printing, extrusion, begins with a polymer rod, or filament. The filament is heated, melted and forced through a nozzle in the print head. It then deposits a layer of polymer in a prescribed pattern, which ultimately results in a freestanding 3D object.
Hart teamed up with Jamison Go and Adam Stevens, also from MIT, to examine the limitations of several commercial, extrusion-based desktop models. Three factors stood out, namely, the force the print head could apply as it pushed the material through the nozzle, how quickly the material could melt and flow and the overall speed of the print head.
The team designed a machine that addresses all these limitations; the design overcomes the limits on force and heating that slows down current 3-D printers; it transfers a higher force to the filament without losing its grip; and preheats the filament with a laser to ensure it’s thoroughly molten by the time it reaches the nozzle.
Amazingly, tests have shown that this new print head can deliver almost three times the force to the filament as that of standard desktop models, and 14 times the extrusion rate.
This rapid extrusion rate required a redesign of the print head, and it now sits on top of a stage connected to a belt which allows for it to be transported quickly and efficiently through the prearranged positions.
A series of test objects were printed to demonstrate the efficacy of the system. It took 3.6 minutes to print a pair of eyeglasses, six minutes for a small spiral cup and about 10 minutes for a circular gear with angled teeth, as seen in the video above.
While the prototype system cost US$15,000— almost two-thirds of the cost was attributed to the laser and motors— it could compete with cutting-edge systems and offer a reduction in operating costs stemming from faster output rates.
Hart also collaborated with a lecturer at the University of Cambridge in the UK, Sebastian Pattinson, to use cellulose as a polymer. This forms another facet of Hart’s sustainable vision of 3-D printing to process materials that are abundant and environmentally friendly.
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Although cellulose is inexpensive, bio-renewable, biodegradable, mechanically robust and chemically versatile, the team were aware that 3-D printing with cellulose had been largely unsuccessful in the past due to the decomposing nature of cellulose when heated.
To combat this, the team created cellulose acetate, which is first dissolved in an acetone solvent to form a viscous feedstock. As the mixture spreads across the print bed, the acetone solvent evaporates, leaving behind the cellulose acetate.
Immersing it in sodium hydroxide restores the cellulose to its original state. You can modify cellulose in different ways, for example, to increase its mechanical properties or to add color,” Hart adds, as he says cellulose provides chemical versatility too.
22 January 2019