Additive manufacturing in aviation

1. Introduction: Why aviation is driving 3D printing

No other industry has driven the development of industrial metal 3D printing as significantly as aerospace. The extreme requirements for quality, weight reduction and the handling of difficult-to-machine high-performance materials make the industry the ideal application area for additive manufacturing (AM).

This white paper highlights the core applications, materials used and the enormous hurdles to certification in this high-security area.

2. Lightweight construction: Every gram counts (topology optimization)

The primary goal in aircraft construction is weight reduction. Every kilo saved reduces kerosene consumption by thousands of liters over the life of the aircraft.

• Bionic hinges (brackets): Brackets with which aircraft doors or cabin parts are attached are classic milled parts. Through topology optimization, the material can be distributed exactly across the force curves. The result looks organic ("like a bone") and weighs up to 50% less with the same strength.
• Seat structures: Mounts for the passenger seats, often printed from aluminum (Scalmalloy) or titanium (Ti6Al4V).

3. Engines and turbines: Fighting the heat

Extreme temperatures and pressures prevail in aircraft engines and rocket engines. This is where standard metals fail; Nickel-based alloys (superalloys) must be used.

• Fuel Nozzles: Probably the most famous AM component comes from GE Aviation (LEAP engine). Instead of laboriously welding and soldering the nozzle together from 20 individual parts, it is now printed in a single piece (PBF). The component is 25% lighter and lasts 5 times as long.
• Turbine blades: Cooling turbine blades increases the efficiency of the engine. 3D printing can be used to create microscopically fine, spiral-shaped cooling channels inside the blades, which are impossible to achieve using casting or milling technology.

4. Space sector: rocket engines from the printer

In the field of space travel (New Space) there is no longer just experimentation; Here the entire production is converted to 3D printing.

• Combustion Chambers: Companies like Relativity Space or SpaceX print entire rocket engines or even large parts of the fuselage. Combustion chambers made of copper alloys (due to the extremely high thermal conductivity for cooling) are manufactured additively because the internal channel structure is classically impossible to produce economically.
• The start-up Relativity Space is even building huge WAAM/DED systems (Stargate) to additively build rocket bodies almost entirely out of aluminum.

5. Certification and qualification

The biggest hurdle for series use in aviation is not the technology itself, but rather approval by authorities (FAA, EASA).

Every aircraft part must be absolutely error-free and reproducible. The challenge in 3D printing is that the material properties (structure) only emerge during the printing process.

• In-situ monitoring: Modern PBF machines (e.g. from EOS or SLM Solutions) monitor each individual melt pool with high-resolution cameras (melt pool monitoring). If pores appear, this is registered at the same moment.
• Qualification processes: Manufacturers must freeze the entire process (machine, powder batch, laser parameters). Only when it is statistically proven that the spread of the material properties is minimal is the component released for flight.

6. Conclusion: The spearhead of technology

Aerospace will remain the most important driver industry for metal 3D printing for the foreseeable future. The investments that Boeing, Airbus, GE and SpaceX put into the approval of processes benefit other industries (such as mechanical engineering) with a time lag as proven "best practices".