Page 19 - 3D Metal Printing Spring 2016

This titanium-alloy 3D-printed bracket, produced on a Concept Laser machine, is used on the Airbus A350 XWB. It’s significantly lighter than the previous part, milled from aluminum.
its AMTC labs, is dedicated to 3D printing nickel materials, including Inconel 718, Inconel 625 and Mar-M 247. Inconel, a blend of nickel mixed with chromium, molybdenum and niobium, can stand up to the extreme heat and high pressures inside of a jet turbine. The nickel com- ponent enhances the corrosion resistance of the alloy, another important charac- teristic in the extreme temperature envi- ronment of the combustor.
Following the success of its first Inconel 718 part demo, the company has begun to produce another part, a rear bearing turbine support, printed with the same material. In order to fly a 3D-printed com- ponent on a commercial airplane, even a relatively insignificant part, the FAA must first approve the metal powder that will be used, as well as the part itself.
“We have to select a powder vendor, and then audit that vendor to Honeywell quality standards,” Godfrey says. “Then we must document how the pow- der is to be received, stored, loaded into the printer and reused after a build. All of that information
Alcoa has invested $22 million in its Whitehall, MI, facility to expand its capabilities to perform hot isostatic pressing of larger 3D-printed metal jet- engine parts. The process improves the mechanical properties of 3D-printed parts made of titanium and nickel alloys.
makes it imperative to minimize the amount of material lost in production. To gauge the amount of waste in the process of making parts, aerospace engineers cal- culate the ratio between the weight of the material used to make a component and the weight of the component itself—the ‘buy-to-fly’ ratio.
The ideal buy-to-fly ratio would be “1,” indicating no loss of material during man- ufacturing. With 3D printing, the amount of wasted material allows manufacturers to approach a buy-to-fly ratio of 1, because any powder left over after printing can be re-used. This not only slashes material costs, but also improves sustainability.
Even more important than sustainabil- ity and reduced material cost is energy efficiency, required to help manufacturers meet ever-stricter environmental regula- tions. It also helps to reduce fuel costs— and the number one way to improve effi- ciency is to reduce the weight of the plane.
To achieve ultimate weight reduction requires an entirely new approach, focus- ing on the design itself rather than the traditional “design for manufacture,” which optimizes the ability of existing tools and processes to make a component. The 3D-printing process makes possible entirely new geometries and topologies, including more organic, or “bionic” designs that never could be realized with subtractive manufacturing (see the article on designing for 3D metal printing, begin- ning on page 24 of this issue).
Printing Aerospace Materials
In addition to lighter-weight designs, lightweight materials also are essential to reducing the amount of fuel required to fly an aircraft. Aluminum is light in weight
and relatively inexpensive, and in addition to wings and airframes, also can be used for smaller non-critical parts such as air- handling systems.
By itself, aluminum has a very low melting temperature and high ductility, so for advanced aerospace applications it often is mixed with other metals to improve overall powder (and part) char- acteristics.
One of the most common aluminum alloys is Ti64, the material
used for the new NAVAIR 3D
Aerospace Metal 3D Printing 3D
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printed part. Ti64 has high strength-to-weight radio and fatigue resistance, as well as improved resistance to corrosion and high temperatures.
Last year, Honey- well became the first company to 3D-print an aerospace compo- nent—an experimen- tal design of an exist- ing tube used on its HTF7000 engine— with the nickel-based superalloy Inconel 718. Honeywell, via
a