Metal Additive Manufacturing Gets a New Use Case in Engine Repair

(Image courtesy of Unsplash/Henry Sutanto.)

Although plastics get much of the focus when it comes to additive manufacturing’s rising relevance across industries, metals also work well as a material for quickly yielding low-cost specialty parts. GE Aviation Engine Services Singapore’s (GE AESS) recent announcement—that its Loyang site is the first maintenance, repair and overhaul facility in the world approved to use metal additive manufacturing for commercial jet engine repairs—illustrates additive manufacturing’s versatility.

In general, metal additive manufacturing relies on heat to turn metal into powder form. A machine can then use the powder to produce an object layer by layer based on digital instructions. This differs from subtractive manufacturing, which often involves cutting metal sheets and bending and forming them to achieve the desired shape.

However, additive manufacturing for metal repair parts works differently than standard 3D printing processes. While CAD is generally the starting point for most 3D-printing projects, it doesn’t work in a repair context in which each part needs to be custom-crafted to reflect unique wear patterns that emerge during use. This represents an additional layer of complexity in the process. It’s also compounded by the critical and high-value nature of the components used by the aerospace industry, which can receive significant wear and tear during operation, yet need to remain in working condition at all times.

One bonus of additive manufacturing in aviation repairs is a faster turnaround. GE AESS Managing Director Iain Rodger said that GE’s Concept Laser M2 Series 5 additive manufacturing machines could cut the time it takes to repair aircraft parts, such as those used in CF6 engines, by 50 percent. In the era of commonplace supply chain impediments, such time savings is a boon for GE’s customers.

The Concept Laser M2 Series 5 can be used to 3D print metal aviation parts, significantly decreasing repair time. (Image source courtesy of GE.)

“Productivity has increased with our employees able to repair twice as many parts in a day compared to the conventional repair process,” Rodger said. “Less equipment is also needed for post-processing, so the floor space required is reduced by one-third.”

GE hopes to soon apply its metal additive technology to the CFM56, which it claims is the best-selling engine in commercial aviation history.

The need to repair high-pressure compressor (HPC) blades illustrates how crucial metal additive technology is to the aviation industry. The blades must spin at high speeds with tight clearances from other components to keep planes in the air. Wind erosion, wear and tear from debris, and atmospheric pressure create the need for continuous repair and frequent replacement of the blades. It also means that thorough analysis and testing are necessary before repaired aviation components are approved for use.

In the past, repairing the blade tips required a lengthy cutting, welding and grinding process to get the right shape. However, GE Aviation’s automated additive manufacturing process is being applied to blade tip repair.

The process begins with image analysis software that maps each blade, rendered unique by wear and tear. Customized instructions are then sent to the Concept Laser M2, which produces a new blade tip that needs minimal further processing. As a result, the system repeatedly saves GE time and money compared to other methods. Additionally, customers get blade replacements more quickly.

Rodger also stated that the additive manufacturing process is more sustainable because it uses less energy and generates less waste, with more blades salvaged and repaired.

Singapore's Economic Development Board has supported metal additive manufacturing for aviation repair. With the nation’s universities training many students in additive technologies, the sector could eventually become central to the aircraft repair supply chain.