Arnold Air Force Base’s Tunnel 9 team seeks to take 3D printing program to next dimension


Arnold Engineering Development Complex Hypervelocity wind tunnel 9 started by adding a few 3D printing systems here and there. It has recently evolved and become a big part of component manufacturing at Arnold Air Force Base in White Oak, Maryland.

“The success of [additive manufacturing] at Tunnel 9 is exciting to say the least,” said Samuel Gigioli, Tunnel 9 Nitrogen Supply and System Engineer. an interest or need for 3D printing parts.”

Gigioli continued, “We can spit out plays in hours rather than weeks. Whether it is a test part or a prototype part, the process further speeds up our operations and can have a significant impact on the success of the Tunnel 9 mission.”

The facility acquired its first 3D printer about seven years ago. They used a small filament-based device that could quickly produce simple plastic parts. However, the printer was quickly put into storage as the prints did not meet the required standards.

During Gigioli’s first summer at Tunnel 9, in 2019, he was tasked with reviving the printer’s capabilities. This included ordering new parts, filaments and materials for the device. The second round with the printer turned out to be more successful than the first.

Following the reintroduction of AM, Tunnel 9 used it to manufacture primarily plastic mounting platforms, devices, gauges, and other similar components. After this breakthrough, Tunnel 9 then acquired two additional 3D printers.

A resin-based 3D printer capable of printing small but highly detailed and solid parts, as well as a dual-filament printer capable of consistently printing large and highly detailed parts have been incorporated into the setup.

In February 2020, a research and development team project involving the additive manufacturing of refractive metallic material was launched at tunnel 9. Gigioli supported this effort, aiming to reduce the time and cost of manufacturing certain parts to high temperature used in the tunnel 9.

“These Tunnel 9 parts endure very cyclical, high pressure and temperature conditions, so the life of these parts is significantly shorter than other tunnel parts,” Gigioli said. “These parts can withstand up to 3,000 degrees Fahrenheit. That’s why refractive metals are chosen because they are metals that can withstand extreme heat with relatively little warping.

A significant achievement of the research and development program was the successful manufacture of a component known as the petal orifice liner. The device is an integral part of high Mach number tunnels and is located between the two split diaphragms that Tunnel 9 uses to act as a high speed valve.

Gigiloi said the AM liner outperformed its forged counterpart that has been used for decades in the facility.

“The part is cheaper to manufacture, faster to manufacture and ship, and is more resistant to cyclic thermal loads,” Gigioli said. “The AM process creates very unique microstructures in the material and as a result the structural and thermal properties of the part are different from those of traditional forged metal billets.”

The Tunnel 9 team has already started working on the next 3D printed part to be applied under high Mach number conditions. This component, a particle separator, would act to remove all airborne particles in the gas flow without impeding mass flow through the tunnel.

Gigioli revealed that personnel from various components of the Department of Defense (DoD) congratulated the Tunnel 9 team on the success of the AM work and expressed amazement at the technology and its potential. Part of the research effort includes demonstrating the potential of AM for the entire DoD.

“Imagine if we extend this process to multiple tunnel parts or even entire systems,” Gigioli said. “Now some DoD components are interested in printing test models or state-of-the-art models. I hope to continue to lead Tunnel 9 down this path and increase our success with this technology.

The DoD has been heavily involved in AM lately, recently becoming a beneficiary of 3D printing technology through Bike3Dpartnership with the Hartech Group.

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