GE is preparing to begin the mass production of 3D printed parts for the GEnx jet engine that powers Boeing 747s. The 3D printed GEnx part, a rib-sized bracket that holds the engine cover open during servicing, will mark the first program certified by GE for its Concept Laser metal AM system. GE Aviation will begin producing the parts this month at its factory in Auburn, Alabama.
The GEnx part in question has been in development for the past 10 months by a team that included GE engineer Peter Martinello. Along with designing and preparing the part itself for 3D printing, the engineering team also had to certify its production system and ensure the Concept Laser machines were “production-proof.”
“The reason we did this project was because it represented several firsts for us,” explained Eric Gatlin, a general manager for GE Aviation’s additive integrated product team. “It’s our first program we certified on a Concept Laser machine, and it’s also the first project we’ve taken from design to production in less than 10 months.”
Ensuring the Concept Laser printers (now GE’s own line of machines) were production ready was critical, especially because the GEnx parts are destined for aircrafts and much comply to stringent FAA regulations. “Minor tweaks here and there are OK in the development phase, but when you get into production, everything has to be locked down,” added Danny Brandel, a lead manufacturing engineer at GE Aviation’s Additive Technology Center (ATC).
90% waste reduction
Interestingly, the GEnx engine part that will soon be mass produced using AM, was not always seen as a prime candidate for 3D printing. Whereas other parts have benefitted greatly from AM redesigns (for instance, 3D printing enabled GE engineers to turn a complex metal fuel nozzle made of 20 parts into a single printed component), the GEnx part was always made from a single piece of metal.
Moreover, because the traditionally manufactured part was already installed into working engines and had been approved by the FAA, GE engineers needed to stay close to the original design.
In this case, the benefits of using additive manufacturing for the GEnx part come primarily from waste reduction. “When the GEnx program kicked off, they just hogged the brackets out of a big block of metal,” Martinello said. “By the time you had the finished product, you cut away more than half of it.”
By 3D printing the part, the GE team has been able to achieve a waste reduction of up to 90%. All there is to machine after the print process are some bolt holes and clevis pins. Still, there were some small redesigns integrated into the 3D printed bracket which have allowed for a weight reduction of about 10%. Moreover, by switching the production to additive, the GE team says it has reduced supplier expenses significantly.
Production-proofing the M2
The other critical aspect of prepping the GEnx part for mass 3D printing had to do with readying GE’s Concept Laser machine for mass production. A team of engineers based in the U.S. and Germany collaborated closely to move this validation process along.
More specifically, the team has been working on the Concept Laser M2 printer, a midsize metal AM system which operates a dual laser system, enabling the production of four GEnx brackets at a time. In certifying the machine, the engineers had to ensure a number of things: that the printed brackets were of identical quality to each other, that the print conditions were consistent and stable, and that air flow was adequate.
For the latter, the team upped the power of a system designed to remove the smoke produced by the lasers. By increasing the power, the team has reduced the risk of soot depositions on the melted metal, which could compromise the density of the printed part as well as lessened the risk of the laser being diffused at all.
The team also installed sensors and high-resolution cameras into the 3D printer to monitor the laser’s power and stability, as well as the oxygen level in the print chamber. Currently, the optimization measures the team has taken have been applied on an individual basis, but GE plans to bring the features to a fleet of printers. “We want to have everything quantified and take variation out of the process,” explained Martinello.
Identifying more components
The GEnx part itself is being printed from a cobalt-chrome alloy, largely because the FAA has already certified the material for use inside aircraft engines. Because the material is more expensive than the original nickel-based superalloy, Inconel 625, the engineers had to optimize the build layout to print as many parts as possible at once.
As mentioned, they have been able to fit four brackets into a single build by arranging the parts like interlocking fingers. “It looks like one of those woodblock puzzles, where all the pieces fit together,” Gatlin added. “When you are printing it, it’s hard to tell whether it’s one part or four parts, but when you cut them off the plate, they separate and you have an aircraft’s worth of brackets in one build.”
The part will go into mass production later this month, following 10 months of hard work. The GE team isn’t taking any breaks though, as Martinello and his team are already identifying more parts that could benefit from being 3D printed. For instance, GE is already working on significant cost- and weight-reduction projects for other engine lines such as the LEAP, the GE9X engine for Boeing’s new 777X widebody jet and military programs.