New capability for 3D printing in metal

A new 3D printer was installed on campus that uses a laser to fuse metallic powder and print 3D parts in metal.  

“We can use any printable metal, but our current focus is stainless steel and Inconel, a superalloy often used in extreme environments like those experienced by vehicles traveling at hypersonic speed,” said David Ehrhardt.  “The metallic additive manufacturing machine can print a full volume of 11” x 11” x 11” with open control of build parameters and advanced imaging techniques to monitor the build process.” Ehrhardt is research professor in the Department of Aerospace Engineering as well as the lab coordinator for the Advanced Material Testing and Evaluation Laboratory.

Ehrhardt said, “When considering the design of supersonic and hypersonic air vehicles, there is still a need to understand how a structure will interact with the air around it in phenomenon termed fluid-thermal-structural interactions. I am involved with several US Air Force projects that are combining analysis with experiments in wind tunnels to develop physics-based predictive models of how thin structures respond in these extreme environments.”

According to Ehrhardt, currently, thin panels used in these tests are machined out of solid blocks of material to limit geometric variations in structures about 0.5 mm thick.  And, although this process works well for producing consistent flat panels for model calibration in these fundamental experiments, future high-speed air vehicles will require complex geometries based on novel design techniques using high temperature materials such as refractory metals, nickel-based super alloys, or oxide dispersion strengthened alloys.

“Traditional machining techniques struggle to produce structures under these constraints, but additive manufacturing expands the design space required for future air vehicles,” he said.

In the project testing flat panels, Ehrhardt said additive manufacturing techniques could be immediately implemented in the design of pre-deformed panels, novel support structures, and potential cooling channels to control the thermal boundary conditions in these wind-tunnel experiments. And although the build volume is small when compared to a full air vehicle, this additive manufacturing machine is the perfect size to expand and explore a structure’s design space in wind tunnels across the country.

“At the university, we train students in additive manufacturing, but metallic printing has been difficult,” Ehrhardt said. “With this equipment, we can foster broader collaboration throughout campus with faculty across many disciplines. In addition to complex geometries, this open additive manufacturing machine enhances our ability to control the microstructural evolution of printed metals through their dependence on build parameters.”

The Open Additive Panda printer is housed in the Illinois Manufacturing Institute’s Large Metal Additive Manufacturing Facility at The Grainger College of Engineering, University of Illinois Urbana-Champaign.

The printer was purchased with support from a Defense University Research Instrument Program award.