Taking advantage of additive manufacturing requires exceptional design and production, but only if the materials used can meet the desired expectations during end use. Though metal 3D printing’s use in production has grown in recent years, there are still many applications where low strength AlSiMg dominates the market.
With the launch of Aluminum 7A77.60L powder, California’s HRL Laboratories functionalized the strongest additive manufacturing aluminum to date. “HRL’s 7A77 is the first wrought equivalent high strength aluminum alloy available for additive manufacturing with strengths in excess of 600 MPa,” comments Hunter Martin, PhD, Chief Metallurgist at HRL Laboratories. “This strength provides exceptional design freedom for high performance application not yet explored in additive.”
Commercially available since October 2019, HRL researchers have begun to explore the industrial applications of 7A77. Already, NASA’s Marshall Space Flight Center has begun applying the material to the production of large-scale aerospace components. Now, working with 3D design and engineering software company nTopology and aerospace manufacturing service provider Morf3D, HRL has built an application presenting 7A77’s potential in heat transfer and flow applications.
High strength aluminum meets generative design
Harnessing the innate thermal conductivity of 7A77’s aluminum content, HRL and its partners have built a generatively designed fuel cooled oil cooler for aerospace applications. In this design, the strength of the alloy is used to meet critical burst pressure requirements while maximizing the exchange of heat with walls thinner than those achieved with conventional AlSiMg. The high yield strength of 7A77 allows heat exchanger designers to reduce wall thickness by 50% effectively doubling the heat transfer performance of a heat exchanger simply by changing the material.
nTopology, a software company building the next generation of engineering design tools for advanced manufacturing, leveraged its computational modeling platform to define a volume that would maximize surface area while minimizing mass. By using a gyroid structure, nTopology was able to generate an internal core with 146% more surface area than a traditional tube and shell structure. By coupling HRL’s high strength aluminum with generative design, nTopology was able to increase the heat transfer rate of the design by 300%.
For all application and material needs
Based in El Segundo, California Morf3D was responsible for the manufacture of the 7A77 heat exchanger. Using one if its fleet of EOS DMLS systems, Morf3D produced a complete heat exchanger design, and two cut-away demonstrators to show the complexity of internal gyroid channels.
The final result is a topological gyroid heat exchanger maximising part strength, minimizing weight, and, crucially, outperforming other additive aluminum alloys. “HRL’s high strength aluminum alloy means flow structures like manifolds, or in this case a topological gyroid heat exchanger, can be manufactured with thinner walls producing lighter weight components and higher performance,” concludes Martin.
HRL Laboratories will be exhibiting its 7A77 material and more at Formnext from 19 – 22 November 2019. Visitors are invited to visit HRL in hall 12.0 booth E101H with all application and material needs.
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Featured image shows the final topological gyroid heat exchanger design, 3D printed as a cutaway to show internal geometries. Photo via HRL Laboratories and Morf3D
