Additive Manufacturing

NOV 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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NOVEMBER 2018 Additive Manufacturing CHECK THIS OUT 72 By Peter Zelinski Army Bracket Illustrates Strange Complexity of Optimized Geometry Topology optimization will introduce strangeness even to simple parts, and the part seen here provides an illustration. I saw it during a recent visit to the Center for Innovative Materials Processing through Direct Digital Deposition (CIMP-3D) at Penn State University. Penn State R&D engineer Corey Dickman gave me its background. The part is a bracket. It was 3D printed for the U.S. Army Aviation and Missile Research Development and Engineering Center (AMRDEC) to replace a more conventionally shaped bracket made through more conventional means. The new, titanium bracket was redesigned for additive manufacturing by Materials Sciences Corp., which employed topology optimiza- tion to realize this form. CIMP-3D produced it via powder-bed fusion. With brackets, one of the most basic assumptions governing their design is the expectation that a bracket ought to obey the same spatial boundaries as the forms it connects. The original version of the bracket (seen at left) did this. However, using mathematical analysis to pursue the Army's twin goals of low mass and high stiffness not only produced a form that only AM could create, it also revealed that the best-performing form extends some of its mass into space the previous bracket did not touch. As topology optimization becomes more accessible thanks to AM, we should expect more of our manufactured world to become weird in this way. This part also illustrates other important points about the advance of additive. Read more at gbm.media/bracket. The brackets as they were built. According to Corey Dickman, the grid pattern seen here helped ensure a more even distribution of powder throughout the initial layers, aiding in realizing a secure bond to the plate. Here is the additive bracket alongside a 3D-printed replica of the bracket it replaced. Compared to the conventional bracket, the topology-optimized version projects some of its minimal mass into previously unused space. Support structures are a significant part of the build—significant in both material use and engineering attention. Learn more about this aspect of the project at gbm.media/bracket.

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