WHY THE HYPE?
wire, polymer filament, powders, liquids, gels, mixtures of glues and materials, and slurries. ASTM International (previously the American Society for Testing and Materials) notes seven primary manufacturing processes. Within those exists a growing list of more specialized methods. It is entirely possible that more have been developed since ASTM’s survey of the state of the art. Tat’s how fast the technology moves.
QUICK AND CUSTOM Quick custom design and build is one of the great promises of additive manufacturing as a category. In theory, every pair of shoes that every Soldier wears could be custom fit and printed to match the contours of a Soldier’s feet. Indeed, at least one major athletic shoe brand makes a shoe that’s entirely additively manu- factured, although it’s not customized to each pair of feet. Yet.
Tat customization possibility extends to both very large objects, such as the buildings that the U.S. Army Corps of Engineers’ Automated Construction of Expeditionary Structures program is making, to the extremely small, such as the 4D robots (the fourth dimension is motion) that the Institute for Soldier Nano- technologies at the Massachusetts Institute of Technology (MIT) recently developed. Dr. Xuanhe Zhao and his team created “soft, magnetic, 3D-printed structures that can transform their shape almost instantaneously by the wave of a magnet.”
Tat speed is the real breakthrough, Zhao said in an interview with Army AL&T, but the use of nanomaterials is nothing to sneeze at. Currently, he said, “the drawback of existing [4D] struc- tures is that their movement [is] very slow.”
Zhao, an associate professor at MIT and a researcher at the Insti- tute for Soldier Nanotechnologies, said, “What we developed is basically a new material system for 3D printing.” In additive manufacturing, conceptually, the process, the design and the materials are all equally important. Zhao’s team’s new method places nanomagnetic particles strategically within the soft plastic. Te placement and orientation of the materials enable controlled, rapid movement. “We use a new stimulation method, which is magnetic.” Watching video of the structures is a bit like watch- ing muscles twitch.
Indeed, Zhao, said, that’s the point. “You can reach the level of energy density and the power density of real muscles. So now, we can make it move very fast and forceful.”
Zhao said the technology that he and his team invented has real promise for biomedical devices that can be customized, but neither the printer nor the ink for the method they used existed, so they had to invent them. “We invented a printing method and the ink so that … researchers can print structures that they want—different shapes of robots, different shapes of actuators— and when we apply a magnetic field, you can actuate it or you can move this object.”
Watching the structures move, it’s not hard to imagine why Zhao said the team envisions them in medical applications. “We are actually trying to simulate the functions of the heart, so the heart beating, and muscle contraction inside the human body. And also, we are making this kind of magnetic materials, 3D-printed into, for example, catheters. But those catheters, you know, are smart. … Tey can steer themselves inside the human body. For example, in the blood vessel, they can make turns. … So that indeed is one … project we are working on.”
“We use four additive manufacturing machines there, which we run 24 hours a day, and what we’re building is going right into the hands of U.S. Soldiers.”
92 Army AL&T Magazine January-March 2019
‘ADDITIVE DOESN’T CARE’ Human beings have been making things for thousands of years. Te word “manufacturing” actually means “handmade,” coming from the Latin for hand (manu) and made (factum), despite current connotations of machine-made.
Doing something for thousands of years means that an almost intuitive understanding of the materials and processes has been passed down from generation to generation. Sloughing off the knowledge built from thousands of years of doing the same thing and perfecting it evolutionarily is not an easy task, and that can be a serious problem for designers—that and the addition of poten- tially millions more variables into the manufacturing process.
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