Additive Manufacturing

JUL 2018

ADDITIVE MANUFACTURING is the magazine devoted to industrial applications of 3D printing and digital layering technology. We cover the promise and the challenges of this technology for making functional tooling and end-use production parts.

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JULY 2018 Additive Manufacturing 12 TAKING SHAPE When Keith Cox talks about 3D printing, he refers to it as a "conversion process." That phrase is an important clue to the role 3D printing is destined to play and the way that companies like his employer will figure in. I recently had a conversation with him about polymer development for additive manufacturing. Cox works for SABIC, supplier of polymer materials, where his role is senior business manager for AM. From his and this company's perspective, 3D printing is indeed another conversion process, one more means (like injection molding, blow molding or extrusion) for convert- ing the raw stock from SABIC into a finished good. The different processes behave in different ways and make different demands on the material. And while 3D printing is the newest such process to appear, tailoring materials to the needs of a conversion process is what the company has been doing all along. In this sense, supporting additive manufacturing as it finds a growing role in production is simply more of the same. But in another sense, AM represents a very different set of challenges for the company. And a different opportunity, because 3D printing promises to grow the very market potential for plas- tics by expanding what it is possible for plastics to do. The challenges first: 3D printing is physically a very different operation from other conversion processes. In fact, it is different operations, plural, because AM processes such as selective laser sintering (SLS) and fused filament fabri- cation (FFF) differ from one another. But both these processes differ markedly from established means of working with plastic such as injection molding. Consider: Injec- tion molding is a hot, high-pressure, short-cycle-time process—the mold slams shut as high- temperature material is injected in. By contrast, both SLS and FFF are processes in- volving little pressure, run only at the melting or extrusion temperature of the material, with a cycle time lasting so long that the material might remain at or near this tempera- ture for hours at a time or even a day. Thus, realizing a polycarbonate delivering roughly similar properties after injection molding or 3D printing entails starting with different formulations of the raw stock tuned to these different processes. The other, bigger area of challenge relates to how dynamic additive still is, and how much is still changing. "The maturity level of the AM space today makes material development complex," he says. "These processes are all evolving. Even in FFF over the last five years, we've seen tremendous change in the 3D printing technology. So we're at a disadvantage both because there is not a lot of history with these processes and because there continues to be a lot of change." And that change plays out not only in the machine hardware, but also in the design and simulation software, which are also advancing and can also affect material application. But it's all worth it, and the reason why gets to the opportunity. 3D printing is funda- mentally different from other conversion processes because there is no tooling needed. There is no mold, for example. That opens the range of part geometries that can be achieved, while reducing the production quantities that might be cost-effective. Because of both areas of freedom, 3D printing will be an enabler for the advance of polymers. By delivering both previously impossible forms and previously impractical solutions, 3D printing will bring plastics into applications it was never able to serve before. Polymer developers obviously see high value in being part of this. AM Will Advance Plastics, But Open Parameters Increasingly Valuable By Peter Zelinski SABIC's Extem is an example of a material potentially stretching the capabilities of the 3D printer. The heat-resistant material for aerospace, automotive and electrical applications demands a high temperature for melting and parameters sufficiently open for the user to select that tempera- ture at the printer.

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