High-Performance Composites is read by qualified composites industry professionals in the fields of continuous carbon fiber and other high-performance composites as well as the associated end-markets of aerospace, military, and automotive.
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4 4 | H I G H - P E R F O R M A N C E C O M P O S I T E S ADDITIVE MANUFACTURING ADDITIVE MANUFACTURING A 3-D Printing of continuous carbon fiber composites? dditive manufacturing (AM) is one of the hottest areas in parts fabrication. Interest is high, re- search dollars are being spent and company stocks are attract- ing investor attention. Why? First, be- cause AM has moved beyond its initial role as a prototyping tool to a process that can build fnished parts. AM tech- nologies — stereolithography, fused deposition modeling (FDM), laser sin- tering (LS), material extrusion, direct metal deposition and more (see "Learn More," p. 47) — were able from their beginnings to accurately form complex, three-dimensional parts directly, without tooling or touch labor. They build them up in stacked, horizontal layers from digi- tal design fles (hence, the moniker "3-D printing"). But those early technologies came with some technical challenges that — particularly in the composites industry — limited their utility. Although they could produce a part, or multiple small parts, faster than many molding processes, early AM devices used low- end, unreinforced commodity thermo- plastics or metals. In addition, machine build enclosures were small, limiting part size. Most importantly, they could easily duplicate part dimensions within specifed tolerances but rarely delivered the mechanical properties necessary in a fnished part. In recent years, however, refned 3-D printers have built parts from a wider range of tougher, stronger ma- terials. Beyond the "cool" factor, these processes now have enormous appeal to industry. Indeed, many OEMs, includ- ing The Boeing Co. (Chicago, Ill.) and GE (Fairfeld, Conn.), have already adopted the technology for complex parts that are fying on aircraft. But until recently, AM offered no viable alternative to molders of high-perfor- mance composites. Some machines can form parts using reinforced plastics, but only very short fbers can pass through the deposition heads. Part strength and stiffness, therefore, could not match that achieved with continuous fbers. A new era of instant awesomeness A recent arrival on the AM scene, Mark- Forged (Cambridge, Mass.) is charting a course that could change that. A small startup, opened in early 2013 by MIT- educated aerospace engineer Greg Mark, it is a spin-off from Mark's Aeromotions company, which produces computer- controlled carbon fber wings for race cars. Although his experience with com- posites began with wet layup, he says, "we then moved to prepreg construction and autoclave cure and, fnally, to out- of-autoclave infusion." But, regardless of the method, the time required to make molds, obtain materials, and then lay up and cure the parts was not trivial — nor was the cost, he adds. "That motivated us to develop our printing technology," Mark explains. "Our vision was always to make end-use parts, but a lot more effciently. We wanted to use the mechanics of a 3-D printer to Additive manufacturing startup MarkForged aims to make it happen — and is already marketing systems. BY SARA BLACK Additive manufacturing with continuous reinforcement MarkForged (Cambridge, Mass.) will soon offer for sale the Mark One 3-D printer, reportedly capable of making printed parts with continuous carbon, glass and, soon, aramid fibers. Source: MarkForged 0514HPC AdditiveManufacturing-OK.indd 44 4/22/2014 3:14:01 PM