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They expand if heated, and it can be difficult to maintain dimensional stability as mold size increases, explains Tim Schniepp, a project manager and additive manufacturing research engineer with extensive aerospace experience at Stratasys (Eden Prairie, MN, US). Heat is problematic, in part, because AM materials are (usually) unreinforced plastic polymers. “But our application envelope is expanding,” he adds, because new materials could expand that space. But tools that must withstand the heat of a cure cycle in an autoclave? These, he says, are more formidable. “AM tools take days … or hours.”Īnother challenge: The use of 3D printing is what Mike Vander Wel, head of equipment and tool engineering for Boeing Commercial Airplanes (Seattle, WA, US), refers to as “application dependent.” Low-temperature, short-run tools for prototyping that won’t see high temperatures, for example, are commonly 3D-printed and well within AM’s scope. “Metal tools take months,” Cottrell points out. But the key is that AM now enables its users to circumvent much of the lead time - much of it, simply wait time - and eliminate many of the multiple toolmaking steps that stand between the molder and the beginning of his first part production-and-assembly cycle. “We’re seeing some really good fits for additive manufacturing in composites tooling,” confirms project engineer Dan Cottrell at Aurora Flight Sciences (Manassas, VA, US). “We’ve been looking at this for years, but now the technologies are getting better,” one tooling expert recently confided to CW, citing the availability of faster, larger and less-expensive AM machines and higher-temperature materials that address some previous issues with rapid moldmaking. Short carbon fiber compounds expand reach of thermoplastic compositesĪlthough AM’s most obvious advantage is direct part production without tooling, the growing trend in the aerospace and automotive sectors at present is its use for fast, on-demand builds of mold tools to keep pace with accelerating composite part design cycles and demand for faster overall part processing speeds.