NOV 2018


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NOVEMBER 2018 12 CompositesWorld TRENDS Continuous fiber manufacturing blurs the line between 3D printing and AFP Strides in continuous fiber manufacturing, new insights into the size of the global aerospace industry, new ways to use pultrusion in the rail sector and more. Continuous fiber manufacturing (CFM) is the 3D printing/continuous fiber deposition process patented by moi composites (Milan, Italy). The company was established in February 2018 by materials engineer and professor Marinella Levi, design engineer Gabriele Natale and architect Michele Tonizzo. It was spun off from the +LAB, a collaborative 3D printing hub that Levi founded at the Politecnico di Milano. CFM was patented in 2015 and demonstrated in 2016 through the Atropos project, which involved printing a continuous glass fiber/epoxy propeller blade using a Kuka industrial robot. The blade featured an internal truss and an exterior shell, demonstrating both a multiaxial laminate (e.g., 0°/+45°/-45°) and fiber place- ment along a nonlinear axis. Moi composites has developed a second-generation system using a Comau robot with a 1.0-by-0.5-by-0.8m height build envelope. "We have also used larger robots with rotary tables and larger build volumes, demonstrating that our technology is easily scal- able," says co-founder Tonizzo. "We currently can print with UV-cure in epoxy, acrylic and vinyl ester," he says, "but we are not tied to UV curing." Glass fibers up to 2400 tex and basalt fibers have reportedly printed well and moi composites is now working with carbon fiber, though not with UV cure resins. The company can also print with electrically conduc- tive fibers and is producing parts for biomedical, marine, oil and gas and aerospace applications, mainly using glass fiber. It is also developing a third-generation, all-in-one print head with a system to apply pressure to the fibers, sensors, cutting mechanisms and a milling tool. Tonizzo says this will close the gap between 3D printing and automated fiber placement (AFP). "3D printing does not achieve the performance of AFP, but CFM offers more flexibility. We can already print with fibers 0.25-mm thick and have the ability to create curves and place continuous fibers in the ideal position," he adds. Hybrid materials processing has been explored by moi composites; one result of this exploration is the Superior- brand lightweight, low-deflection lower limb prosthesis. The prosthesis is made with a printed continuous glass fiber internal core that is then sheathed with a hand-laid, vacuum bag-only cured carbon fiber/epoxy skin. "The whole design reduces deflection and increases customization Continuous glass fiber and UV-cured vinyl ester resin are deposited along nonlinear curves in 3D space to form the back fork of a BMX bike frame using the CFM process. Source | moi composites while significantly cutting cost and production time," says Tonizzo. Part of this optimization is produced through the digital design and workflow, which uses Autodesk software with moi composites' algorithms for stress and path optimiza- tion. This is what produces the optimized fiber path for the structural loads and fiber deposition process. CFM is open to a variety of materials and design innova- tions explored by +LAB, including 3D-printed infill patterns with a tunable elastic response, and printing with novel matrices like geopolymers, which behave like concrete. As moi composites continues advancing its CFM technol- ogy, will it sell print heads and machines? "Yes, but in the future," says Tonizzo. "For now, we are producing parts and bringing the technology to the client's facility, using our know-how, print head and software to realize part solu- tions on demand. We are also seeking investors to further scale CFM machines and processes for commercial market opportunities." Read more in the online blog |

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