Page 36 - 3D Metal Printing Spring 2018

3D Arconic Goes All-In on AM
Fig. 2—Made of Inconel 718 nickel, vent tubes printed for Lockheed Martin and used on the NASA Orion space capsule originally consisted of six parts welded together in a process that took weeks. Produced via AM in only 40 hr. as one part, including screens, four tubes fly on the Orion.
microstructure and allows the develop- ment of new AM alloys that cannot be produced using the traditional ingot-pro- duction process.
“Resulting from such research,” he continues, “Arconic is developing a high- temperature aluminum alloy that per- forms in temperatures to 450 F, almost unheard of for aluminum alloys. For example, at 450 F, 6061 aluminum has a strength of about 350 MPa, while our new powder-bed AL alloy exhibits a higher tensile strength. This opens up new part possibilities for aluminum.”
At the Arconic Technical Center, the company atomizes nickel, aluminum and titanium powders, to develop new alloys and better understand the powder-making process. The payoff: metal powders opti- mized with the properties needed to print better-performing parts.
Looking to Larger Parts, Too
Beyond smaller, detailed parts, Arconic employs AM to produce larger parts as well. “We make some very large titanium and aluminum forgings, nickel discs and similar types of parts,” says Colvin. “We bring material to a controlled temperature and give it a 3D shape. These fundamen- tals apply to our traditional processes and
the same holds true for AM.”
By mid-2015, the company was oper-
ating the Sciaky HDR AM machine at its technology center, and learning how to produce AM-optimized larger parts that meet stringent aerospace standards.
“Arconic has a long history in develop- ing new materials and processes, so we have a wealth of experience in undergoing testing, qualification and approval,” Colvin says. “Of course, the larger the part, the more places we have to check to meet all of these requirements. Our larger parts may have less detail than some of the smaller parts, but much more volume and more metal being deposited, and deposit- ed much faster. As part size increases, there are more layers and they get longer, and every layer has an interface where we must ensure integrity. We have to ensure reliable deposition and, as we have very high performance criteria, the materials
of the microstructure as it cools very quickly from a molten to a solid state. If we understand that, we can achieve better and more consistent mechanical proper- ties needed for aerospace applications.”
Arconic boasts an array of powder-bed machines—including EOS, Renishaw, SLM Solutions and ExOne—to produce metal parts for Airbus, Lockheed Martin and other aerospace heavy hitters. The company has expended much effort in researching and developing processes, and understanding microlayer behavior and characteristics, then getting machines to perform at their best via optimized parameter settings.
“You tune machines with printing parameters that get you from point A to point B,” Larsen says. “This is where many companies have issues. Either they buy machines without the needed parameter adjustability, or they don’t understand that parameter adjustment is so critical.
“We can examine the AM process layer by layer,” he continues. “In the future our goal is to identify potential problems during production of each layer, and fix them in- process. When we qualify a part for an aero- space customer, we must establish a fixed process with inspection steps to ensure that we produce defect-free parts. That all goes back to the metallurgy and the printing parameters. The best parameters end up producing a part with the lowest porosity. When post-processing, including hot iso- static pressing, if we only have a couple of pores, we likely can close those pores.”
Though today Arconic often employs AM to reproduce parts formerly manufac-
tured using traditional processes, the com- pany is working to design parts with 3D- printing capabilities in mind as customers become more comfortable with the process, offers Larsen. An example: airframe brack- ets with designs optimized for laser-pow- der-bed production.
“When we do that, we can produce, say, 50-percent-lighter designs—struc- tures that look very organic but use 50- percent-less material—that perform the same functions,” he says. “Our goal: opti- mized designs that only place material where it is needed.”
Arconic, via the laser-powder-bed process, also has found success joining multiple parts into one structure printed as a single piece. A perfect example: vent tubes produced for Lockheed Martin and used on the NASA Orion space capsule. Made of Inconel 718, each tube is the size of a 1-L water bottle and originally con- sisted of six parts welded together in a process that took weeks. Produced via AM in only 40 hr. as one part, including screens, four tubes fly on Orion.
“Part of our job is to educate potential customers and designers, and unlock their design space to an area where they have never been,” says Larsen. “We want to open minds to a new level of design freedom.”
Freedom also arises from developing new alloy-powder blends and delivery, and Arconic has been busy in this area as well.
“The powder is our smart ink, and we can optimize how powder flows to print the best parts,” Larsen explains. “Rapidly solidifying layer by layer influences the
34 | 3D METAL PRINTING • SPRING 2018
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