C4iSR: Joint & Common Equipment

AFRL pursues 3D printing technology

21 November 2017
Shown is a copper alloy 3D-printed thrust chamber assembly for an Aerojet Rocketdyne RL-10 rocket engine, undergoing hot-fire testing. Source: USAF

The US Air Force Research Laboratory (AFRL) is examining whether three-dimensional (3D) printing can be used in a safe, reliable manner, for aircraft parts.

Doing that will require that the part be based on the design process, understanding how much strength is needed, as well as the criticality of the part to be manufactured, Dr Jonathan Miller, a materials scientist and the additive manufacturing lead at AFRL, told Jane’s .

But 3D printing parts can make them susceptible to fatigue.

“Additive manufacturing behaves poorly in that way because if you just print the parts and you leave the surface like it was printed that is where you initiate all these fatigue flaws and cracks,” Miller explained. “So, what I have to do is machine off all those surfaces to get it to work.

“This is the type of research we are doing to learn and understand where we can use additive manufacturing and what kind of boost processing we need to do, [for] what applications, based on the design requirements of the parts,” he said.

One area where the materials are actually sufficient and work well is environmental ducting that feeds air into the cockpit. Because the ducts are one-off, unique parts and shapes that were made decades ago are ideal candidates for the 3D printing. Additionally, the tooling to make them no longer exists.

AFRL has had success printing the ducts using plastic material. The effort has resulted in significant lead time and cost improvements simply because the air force didn’t need to buy hundreds of ducts, they just needed 10.

But the same material doesn’t work well for other parts. The plastics are not airworthy, most of the time, because they lack the ability to withstand high temperatures.

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