When Thomas Edison made his carbon filament breakthrough in the development of the incandescent light bulb in 1879, the light emitting beyond the glass bulb would last only a matter of hours. Innovative though it may have been, it was ultimately insufficient for the world we were threatening to build.
Edison and his peers persevered, however. The development of a bamboo filament upped the lifespan of a light bulb to 1,200 hours, and the tungsten filament pushed things further along again. Today, fluorescent light bulb technology lasts tens of thousands of hours, and LED lighting technology can last hundreds of thousands.
As Edison spearheaded the research and development of light bulb technology in the US, and separate teams worked to push the envelope across the Atlantic Ocean, he merged his Edison General Electric Company with Thomson-Houston Electric Company to form General Electric (GE) in 1896.
Fast-forward 130 years and General Electric has established itself not only as a leader in energy, but also healthcare and aerospace. And through its endeavours in the latter, it has invested heavily in additive manufacturing (AM), a suite of technologies that have a not too dissimilar trajectory to the light bulb, according to Benito Trevino, General Manager for GE Aerospace’s Additive Integrated Product Team (IPT).
“The first light bulb lasted several hours, and that’s not sustainable for what we need in the world,” he says. “Now, they last thousands of hours. Same thing here. We need that breakthrough in performance so that we can really unlock all the possibilities of additive.”
Thinking additive
Trevino is speaking on a Friday afternoon, dialling into a meeting set up after a tour of GE Aerospace’s Additive Technology Center (ATC) in Cincinnati, Ohio, hosted by ATC Site Leader Chris Philp. His voice is being sent across the airwaves to provide insights on strategy, supplementing those given by Philp on the ground.
During the tour of the ATC, it is made clear that GE Aerospace has a big play with additive in the defence sector, particularly through the development of its T901 engine and its work with the US Army AH-64 Apache and Sikorsky UH-60 Black Hawk military helicopter contracts. Much of the evidence of this work is shielded by coverings and rooms that require authorised access, but it is referenced at regular intervals. GE Aerospace’s most renowned additive manufacturing applications – such as the LEAP fuel nozzle – have so far been produced for commercial aircraft, but it is clear that defence is now firmly on the agenda.
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“We’re seeing a significant increase in interest on the military front,” Trevino offers. “This, coupled with an increase in complexity of the hardware, is pushing the technology to the limits. We want to seize on the opportunity ahead of us.”
“When we first started using additive manufacturing for LEAP and 9X, GE had big commercial engine programmes coming through,” Philp adds. “So, we were able to use those engine tests to validate the potential of additive technology and the rest is history. We built our reputation internally within GE as something that we should be thinking about with new engines going forward. Now, new engines, such as Catalyst, T901 & XA100, were designed with additive capabilities in mind from the beginning.”
Behind the scenes
When GE Aerospace first began applying additive manufacturing to parts for its mature engines around a decade ago, they were typically replacing existing components one-for-one, as the application warranted. Some of these components, the ones that kickstarted GE’s journey with additively manufactured end-use parts, are presented on a table to the left as we step foot on the factory floor. They visibly grow in size and complexity and lead the eye towards a poster of the Apache and Blackhawk helicopters adorning the back wall of the facility.
The application showcase is concluded after 20 minutes, and Philp is now leading us beyond a fleet of Concept Laser X Line 2000R machines, detailing their 160-litre build volume and dual-laser capability. The X Line systems sit beneath the vast office space, which is situated within an octagon structure that has several walkways out onto the shop floor, encouraging members of the team to engage with the work being carried out down below.
We keep walking. Philp points out the locations of the facility where such things as prototyping, powder handling and machining are carried out. The conversation eventually lands on inspection and in-process monitoring. As a development centre, GE Aerospace accepts that things will go wrong with its print jobs, but there’s an emphasis on understanding why, and doing so quickly.
“We’re flying people all over the world, we have to get it right,” Philp later remarks. Such is life, the company expects issues often happen overnight or over the weekend when building parts on the additive printers, so camera technology is used to record print progress, and recoat analysis tools have been implemented to analyse the builds layer by layer and flag any defects. Pictures are taken before and after each recoat, with an algorithm then looking into the pixelation to identify any peculiarities.
“It's an important part of our development process,” Philp says. “I think it's useful enough that we want to implement this in high volume manufacturing as well, we want to be able to walk down a line of 50+ machines and not have to go and peer in the windows. Instead, you're just walking past and you're looking visually at the monitors.”
Everyday I write the book
The work carried out at this facility is of mighty significance to GE Aerospace’s application of additive technology - it is one of several sites that will receive additional funding this year as GE invests 650 million USD into its manufacturing locations. And it is here where GE engineers push 3D printing technology to its limits, understanding just how much they can achieve. The machines are said to be designed to run 24/7, and so GE Aerospace is happy to have some of its machines run jobs that can take several weeks to complete. Although there are plans afoot to bring such times down by more than half – more on that later.
The ATC is a hub of application development. Once the team here have smoothed out all of the bugs, set the parameters and inspected the components, production can commence at another facility, and the aircraft that installs GE’s engines can start enjoying some new performance, cost, and weight benefits. Those benefits are coming at such a pace now that GE is ‘thinking additive’ when it approaches the designs of components and systems.
There are even parts that, on the surface at least, bring no weight, cost, or performance benefit in isolation, but when integrated into an engine serve to improve the performance of those parts around it. The GE9X, for example, is equipped with eight 3D printed cyclonic inducers. These parts add weight and, in isolation, ‘wouldn’t buy themselves onto’ the engine but work to remove dust from the system and reduce wear on other components.
“We challenge the team ‘what is the benefit to the engine, what is the benefit to our customer, by moving this part or designing this part using 3D printing technology?’” Philp says. “As we mature, and as we grow, and as we industrialise, our costs will come down.”
“We’re evangelists,” Trevino adds. “We believe in the technology, but we’re early. We still haven’t matured the cost to the point that you could take two components side by side and say additive wins every time. So, we have to be disciplined about making the right decisions for parts. I think in the future – 10, 15 years from now – as the printer technology advances, there will be a time in which you will take components side by side, and it’ll be a no brainer to proceed additively.
“It’s early, [but] we’d like to think that we’re some of the key authors that are writing this whole additive manufacturing chapter. As I think forward, I am very hopeful that it’s going to be the way we produce hardware in the future. We have to have the intestinal fortitude to be part of that change and to push the envelope on the advances of the technology.”
Read more | A flying start: GE Aerospace's additive manufacturing journey
Learning lessons
Despite the AM evangelism and the intense belief in the capabilities of 3D printing technology, GE Aerospace remains an engine manufacturing business. And as such, it does right by the engine, rather than whatever it can to incorporate AM technology. It is not unheard of for the ATC to get some way down the development process on an additively manufactured part, only to pivot when it becomes clear they won’t hit all the requirements.
“We pivoted away a couple of years ago on one of the parts for one of our engines because it was becoming difficult to manufacture to what our design engineers needed,” Philp explains. “We had learned a lot, but we hadn’t quite gotten across the goal. In that case, for the sake of the engine program, we decided to pivot away, but applied these critical learnings into future additive applications.”
“We’re not here to be right, we’re here to get it right,” Trevino adds. “Sometimes you have to back the train up. We’ve learned a lot over the last ten years. And the decisions we’re making today are much more informed than they were in the past. We also have a lot of structure that we put in place, technical pyramids that bring together technical fellows from across both engineering and supply chain, across all our global sites, to define design practices.
“There are certain criteria that you evaluate as you produce a drawing. For instance, what do you put on the drawing notes, what tolerances will be producible using the additive process etc…, and we didn’t have answers to those out of the gate. We’ve been developing them for the last ten years.”
These best practices are only possible because GE Aerospace has allowed the ATC to try, and fail, and learn over the last decade. The results have positioned the company as an additive manufacturing leader in the aerospace market, with GE Aerospace confident in its proficiency across alloys, parameters, and machines. It does, however, believe the industry is only scratching the surface when it comes to applying additive manufacturing.
Influencing Additive
As GE Aerospace scratches, it is determined to push the capabilities of the technology forward. On the ATC shop floor, there are modified machines to enlarge the build volumes, allowing GE to tackle larger components for its engine systems.
For the applications already under development, GE Aerospace predominately has utilised single-laser metal machines to develop their components. However, going forward, GE Aerospace will be tapping into multi-laser metal additive manufacturing technology for production applications, and has opted to step into that realm hand-in-hand with GE Additive. At the back of the ATC is a black curtain, behind which a team of several engineers from both GE Aerospace and GE Additive are positioned around the quad-laser Concept Laser M Line systems, brainstorming how to advance the technology.
There are four M Line systems installed at the ATC, with a fifth installed at Avio Aero’s Turin facility in Italy. The machine was launched by Concept Laser in November 2016, around the time GE Additive acquired the company. It has undergone around 300 design improvements since then, with GE expanding its build volume to 500 x 500 x 400 mm, and also investing time into how the four lasers work in harmony to build parts.
“When we started working with GE Additive on the concept of the M Line, that was our focus straight away,” Philp says. “How can we have four lasers working together at the same time to build a part faster without taking a material debit? Because we’ve developed the parts on single laser machines, we now want to improve efficiency by using multi-lasers, without changing the quality of the parts we produce.”
This is the kind of platform that GE Aerospace expects to bring its month-long build jobs down to around two weeks, and it is here where GE Aerospace sees the fruits of setting up the GE Additive business. Just this morning, Philp was on the phone with counterparts at GE Additive, and the site’s close proximity to the GE Additive base in Cincinnati allows staff to go between sites easily. Through their work together, GE Aerospace is able to make recommendations via a short feedback loop.
“When we look at expansion, we have a huge growth opportunity and we have to go quad [lasers] because we need to get the efficiency,” Philp explains, “otherwise we’re building multiple factories instead of one. Floor space is critical.”
“We are fortunate,” Trevino offers. “With the power of GE, we are a super user in terms of manufacturing and development [and] we’ve got a sister company that builds machines, and we also have a Global Research Centre in New York [that is] literally full of PhDs. Working together, the three of us, we’ve been able to work out how to develop multi-laser stitching for the additive industry, which is going to be the key.”
Also essential is patience. The M Line was first introduced seven years ago, yet work is still ongoing to develop a process with the utmost stability and consistency, so that when GE Aerospace goes into production with parts and systems, it can do so with confidence. GE Aerospace has made great strides with the technology over the last decade but is also aware enough to know that there is so much more to do and so much further to go. The company understands that there is more to do than just plug an additive manufacturing machine in to get what the machine provider’s brochure tells it, and it is not shy of doing that work.
“We've learned by doing and in some cases, learned the hard way on certain things, but we're better for it,” Trevino finishes. “And I know we'll have a lot of painful lessons as we move forward. But every difficult technology goes through that, [just] like Edison. Edison, how many materials and systems did he try before we arrived at the carbon filament? He tried hundreds, had sleepless nights, and now we enjoy the light bulb.
“I like to think that when we look back at additive manufacturing in the early phases that it's people like those who work at the Additive Technology Centre who are making that a reality so that other people in the future will look [and say,] ‘Oh, anyone could have done that.’ But the reality is, it takes people with very unique skillsets, and a passion for innovation, and an intestinal fortitude [but] you're going to have some sleepless nights, you're going to burn the midnight oil to get there.”
