American manufacturing continues to redefine itself, having recorded growth every month since July 2013 and continuing to focus on advanced manufacturing and building upon traditional American strengths in computers, software and automation. Examples of these efforts often partner academia, public and private entities.
For instance, more than a year ago Notre Dame became a research partner in three advanced manufacturing institutes, which were established as a part of the National Network for Manufacturing Innovation (NNMI), an ambitious program intended to revitalize the national manufacturing sector. The University was one of only two universities to be named a partner in both Chicago’s Digital Manufacturing and Design Innovation Institute (DMDII) and the Lightweight Metals for Tomorrow (LIFT) Institute. Notre Dame also joined America Makes, a national institute focused on additive manufacturing [known to most consumers as 3D printing]. The goal of these partnerships is to increase the nation’s global manufacturing competitiveness and create a robust and balanced community of standards, tools, education and research for a brighter tomorrow.
Most recently, America Makes awarded grants to nine teams, with approximately $8 million in funding and $11 million in matching cost share for applied research and development projects in additive manufacturing. Notre Dame is heavily engaged in these efforts, with the University serving as the team lead on one of these projects and partner institution on another.
Steven R. Schmid, professor of aerospace and mechanical engineering, leads the first project “Economic Production of Next Generation Orthopedic Materials through Powder Reuse in AM.” Well-known in the manufacturing sector, Schmid serves as president of the North American Manufacturing Research Institute of the Society of Manufacturing Engineers and is the author of the well-known manufacturing books Manufacturing Engineering and Technology and Manufacturing Processes for Engineering Materials.
Notre Dame’s research partners on this project include Case Western Reserve University; SCM Metal Products, Inc.; Johnson & Johnson (J&J); and Zimmer Biomet.
According to Schmid, in high-performance additive manufacturing involving powder bed processing, between 5-20% of the powder used in the process is actually fused into useful parts. Because of quality standards equipment manufacturers require that unfused powder be discarded. This means that the material cost in the final product can be as much as ten times higher than the powder cost. Using titanium powder as an example, the actual material cost of the powder can be as much as $400 per kilogram.
As part of this $650K grant, the team is investigating the effect of the thermal cycles that the powder undergoes in an additive manufacturing machine so that the designers can compensate for powder reuse and achieve significant economic gains. Schmid believes by studying the characteristics of the unused powder, its oxygen content, its molecular weight, its flow characteristics and compressibility, it should be possible for a powder to be used up to 20 times.
Notre Dame will lead the mechanical characterization efforts, including fatigue performance evaluation. Zimmer Biomet and J&J will also lead tasks in specimen manufacture and will be heavily engaged in characterization. Some of the testing will be performed in collaboration with Zimmer Biomet and J&J in nearby Warsaw. Case Western will perform material characterization tasks. SCM Metal Products will characterize powder morphology, flow and compressibility characteristics.
“Through our partnership with America Makes as well as other companies and educational institutions, we are taking a leadership role to stay on the forefront of this promising technology,” says Joe Budzinski, director of the Global Development Center at DePuy Synthes. “These projects will help us improve our understanding of the potential value that 3D printing brings to the product development phase so we can advance the full supply chain process, bringing innovations to our customers more quickly.”
The second project, funded at approximately $805K and titled “Parametric Design of Functional Support Structures for Metal Alloy Feedstocks,” is being led by the University of Pittsburgh (Pitt). Notre Dame, J&J, and Indiana Technology and Manufacturing Companies (ITAMCO) round out the team working to develop the design rules for support structures used in Direct Metal Laser Sintering (DMLS).
Support structures are essential to laying part foundations and providing structural support during part builds in 3D printing. They are equally as important in eliminating part warp and improving heat extraction. However, the guidelines for designing support structures are fluid in nature, developed by exploration rather than a specific set of rules. Moreover, while 3D printing machine tool software packages have the ability to add support structures, the existing capabilities are fairly primitive as they do not take into consideration part orientation, distortion, or heat extraction uniformity, all of which can affect structural stability.
David Hoelzle, assistant professor of aerospace and mechanical engineering at the University of Notre Dame who specializes in the material delivery in 3DP processes and control systems theory and application, will lead efforts to produce a heat transfer model for DMLS in order to optimize part orientation, minimize support size and number, produce thermal mass, and predict temperature gradients in relation to the supports. This is the first task in the project.
Other partners (J&J and Pitt) will then perform a design study using part artifacts they print using the model designed by Hoelzle and the Notre Dame team. Once Pitt performs a complete process, geometric, and microstructural characterization of the printed artifacts, ITAMCO will develop support design software that would be integrated into an Autodesk Inventor solid modeling package and would also be transitioned into a cloud platform for dissemination to the America Makes membership prior to commercial development and mass distribution.
According to Joel D. Neidig, business development and technology manager at ITAMCO, “Additive manufacturing will give us the ability to design and manufacture in a way that would be normally impossible for traditional methods. The project will give us the ability to take some of the guesswork out of how to orientate our models and designing supports structures for additive manufacturing.”