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Transformation In 3D: How A Walnut-Sized Part Changed The Way GE Aviation Builds Jet Engines

A jet engine fuel nozzle doesn’t look like much. Shaped like a water faucet perched atop two stubby legs, it resembles a forgotten piece of plumbing equipment small enough to hold in the palm of a hand. Few would ever guess that this unimposing object is among the most disruptive pieces of technology in GE history — one that gave rise to the world’s best-selling commercial jet engines, ignited a new GE business unit and showed the world just what 3D printing can do.

In just a few years, 3D printing, also known as additive manufacturing, has evolved from an alienlike technology confined mainly to labs to a bona fide manufacturing method ready for prime time. GE has already started using it to mass-produce parts for jet engines. In October, GE Aviation’s 3D-printing facility in Auburn, Alabama, produced its 30,000th fuel nozzle tip.

It all started a decade ago, when CFM International, a 50-50 joint venture between GE Aviation and France’s Safran Aircraft Engines, was developing the LEAP engine, a new commercial jet engine that promised to burn less fuel than existing engines and release fewer emissions. As ambitious plans for the engine unfolded, Mohammad Ehteshami, the head of engineering at GE Aviation at the time, quickly recognized its success rested in many respects on the labyrinthine passages inside the tip of the fuel nozzle, which is designed to mix jet fuel with air in the most efficient manner.

To get the job done right, Ehteshami assembled a top-notch team of engineers, including an amateur pilot named Josh Mook, then just 28 years old, whose work with turbine blades had caught Ehteshami’s attention. Before long, Mook and his colleagues came up with their dream variant, a walnut-sized object that housed 14 elaborate fluid passages.

But as elegant as it was, the part arrived with a flaw: The tip’s interior geometry was too intricate. It was almost impossible to make. “We tried to cast it eight times, and we failed every time,” Ehteshami recalls.

Above: Rather than 20 pieces welded together, the new tip (inside the punctured ring section on the right) was a single elegant piece that weighed 25 percent less than its predecessor, and was five times more durable and 30 percent more cost-efficient. Top: Josh Mook stands next to a LEAP engine. Images credit: GE Aviation.

Traditional methods wouldn’t cut it, but 3D printing just might. A 3D printer functions like a laser pen, following a computer drawing and fusing layer upon layer of fine metal powder into the final shape. 3D printers can build complex, dense parts like the fuel nozzle while generating a fraction of the waste produced by conventional manufacturing. The catch: At the time, GE Aviation used additive manufacturing only for prototypes. It had never printed anything for commercial use, much less for an entire fleet of passenger airplanes.

For Mook, who obsessively tinkered with machines as a boy, this was the dream job. Working closely with 3D-printing pioneer Greg Morris — whose company GE eventually acquired — Mook helped re-engineer off-the-shelf 3D printers to meet the fuel nozzle’s specifications. Rather than 20 pieces welded together, the new tip was a single elegant piece that weighed 25 percent less than its predecessor, and was five times more durable and 30 percent more cost-efficient.

But the team was far from finished. They had to work fast to meet the LEAP program schedule and make sure that the Federal Aviation Administration certified the part. And with orders for the LEAP engine pouring in, GE Aviation needed to figure out how to get its 3D-printing operations ready for mass production. “People think 3D printing is as simple as operating an ink printer, but it’s not,” says Chris Schuppe, who runs GE Additive’s AddWorks team, a group of almost 200 engineering consultants dedicated to accelerating additive adoption for GE’s customers. “The fuel nozzle requires orchestrating over 3,000 layers of powdered metal that are about the thickness of a human hair.”

A 3D printer functions like a laser pen, following a computer drawing and fusing layer upon layer of fine metal powder into the final shape. Image credit: Avio Aero.

GE Aviation assembled a new team of roughly 100 employees, ranging from aviation experts to metallurgists, to hammer out these complex processes. That included making sure each machine was properly calibrated to handle the given product’s material properties — an arduous procedure that must be repeated every time a manufacturer adds a new machine to the production line.

And in 2015, it built the fuel nozzle a 3D-printing facility of its own, in Auburn. With more than 40 3D printers at the ready and a deep pool of talent from Auburn University, the plant delivered a total of 8,000 fuel nozzles in 2017. And, as of now, the total tally stands at over 33,000 3D-printed fuel nozzle tips.

There’s much to celebrate with this milestone. The factory supplies fuel nozzles for engines that power both the Airbus A320neo and Boeing 737 MAX jets, with total orders for the LEAP engine exceeding 16,000, valued at more than $236 billion.

Beyond the LEAP engine, GE Aviation uses additive manufacturing to make sensors, blades, heat exchangers and other parts for engines like the GE9X, the world’s largest jet engine, developed for Boeing’s new 777X wide-body plane. The technology even broke into the small-aircraft industry with Catalyst, GE’s new turboprop engine. Engineers used 3D printing to replace 855 components with just a dozen.

But aviation is only the beginning. Today the automotive, energy, healthcare and other industries are embracing 3D printing. GE estimates that by 2020, its GE Additive unit will continue to increase its revenue from equipment, materials and services. Amazing what can grow out of one little walnut.

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