Industrial gas expert Linde announced progress in its joint project with aerospace company Liebherr-Aerospace Toulouse SAS to optimize the metal additive manufacturing process. The companies teamed up to improve aluminum AM production for aircraft components by tweaking oxygen levels in the print chamber. At this stage, the companies have reported improvements in product quality and production repeatability.

In the ongoing collaboration, Linde has offered its ADDvance O₂ precision gas analysis technology, which has played an important role in advancing the AM process. The technology provides continuous analysis of the gas atmosphere in the print chamber, detecting O₂ concentrations with accuracy (as low as 10 parts per million) without cross-sensitivity. The system is also built to purge oxygen to maintain the required atmosphere.

Aerospace company Liebherr-Aerospace Toulouse SAS is seeking to adopt 3D printing for the production of aircraft parts in order to benefit from reduced production surplus and improved manufacturing efficiency. The project with Linde has aimed to validate the technology for its aerospace applications. One of the key aspects of the pilot project has been to develop aluminum 3D printed parts, including bleed air valves.

Earlier on in the project, the aerospace company reported generally positive results, though was still concerned with inconsistent oxygen levels throughout the print process. The fluctuating oxygen levels were compromising the quality of finished aluminum parts.

“Linde has always played a pioneering role in the development of atmospheric gas technologies,” said Pierre Forêt, Senior Expert Manufacturing, Linde. “That we were selected by Liebherr-Aerospace Toulouse to collaborate in this important project to advance the understanding of the role atmospheric gases play in additive manufacturing of critical aerospace parts, is further testament to our innovative capabilities.”

The ADDvance O₂ system was implemented to regulate oxygen levels in the print chamber. Despite its efficiency, however, impurities can remain even after the purging process. These impurities, no matter how small, can influence the mechanical and chemical properties of oxygen-sensitive alloys like aluminum or titanium.

Still, the ADDvance O₂ technology has enabled Liebherr-Aerospace Toulouse to achieve precise, granular control over oxygen concentrations in its metal 3D printer chamber, allowing it to test various levels of oxygen to see how it impacts printed components. The technology improves monitoring and control through a feedback loop with dynamic adaptation, allowing users to define a setpoint value and maintain that value inside the print chamber.

In addition to controlling oxygen levels, Liebherr-Aerospace Toulouse also found that the ADDvance O₂ system was suitable for measuring humidity levels in the print chamber—another element that can make or break a 3D printed part.

“We know that gas purity during fusion has a direct impact on the mechanical and metallurgical properties we can expect to achieve—especially with aluminium alloys,” said Frédéric Letrange, AM Project Leader at Liebherr-Aerospace Toulouse. “So, we needed a dedicated solution to help us improve atmosphere control in the printer. Having looked at the various oxygen measurement and control systems available on the market, it quickly became clear to us that ADDvance O₂ precision was the most mature so it was a natural step for us to expand our partnership with Linde into the additive manufacturing space.”