The future of aviation and metalworking's response

Aviation faces significant challenges: On the one hand, more and more aircraft are needed, while on the other, society is pushing for climate-neutral solutions. Prof. Dr.-Ing. Jan Dege from the Institute for Production Management and Technology (IPMT) at TU Hamburg highlighted in his presentation at the Aerospace Days, hosted by Walter Tools and Heller, how modern manufacturing technologies can help solve these problems.

Increasing demand for aircraft

Global aviation is continuously growing. According to market forecasts, over 42,000 new aircraft will be needed by 2043. This demand is driven by new routes and the replacement of older models. International crises like the COVID-19 pandemic may cause a temporary dip in demand, but they cannot halt the overall trend, which has devastating consequences for climate change. The problem is not new, and some effective measures have already been implemented: "If we compare the current situation with the 1980s, emissions per passenger kilometre have been reduced by 50 percent through optimised aerodynamics and advanced materials," says Jan Dege.

Progress towards decarbonisation

The aviation industry aims to be climate-neutral by 2050. A significant portion of the emissions reduction at Airbus is expected to be achieved through sustainable aviation fuels (SAF) and new aircraft technologies. Additionally, the company aims to take a pioneering role with the "Zero E" study: Three models powered by hydrogen or sustainable kerosene should be in operation by 2035. However, it is already foreseeable that the project will be delayed by at least five years due to the slow development of hydrogen infrastructure. Comparing conventional aircraft with hydrogen models also reveals a central challenge: the lower volumetric energy density of hydrogen, which significantly increases the space required for fuel tanks. This not only means shorter ranges but also fewer passengers.

The role of manufacturing

With the fuel issue, the CO₂ balance of aircraft production itself comes into focus. "Take the A321 XLR: When this aircraft is powered by kerosene, about 98 percent of CO₂ emissions over its entire lifecycle are generated during operation, and only two percent are attributed to manufacturing, making its emissions less significant. If we switch from kerosene to sustainable fuels, 20 percent of emissions come from operation and 80 percent from manufacturing," explains Dege. "For zero-emissions aircraft, it will be nearly 100 percent." Thus, manufacturing will face increased pressure to reduce its own emissions in the future. A significant lever here is the material. For example, in the production of large metallic structural components like the door frame or ribs, up to 95 percent of the raw material is turned into chips, resulting in a buy-to-fly ratio of 22. This leads to unnecessarily high energy consumption for raw material extraction.

Alternatives to conventional manufacturing

But how can this ratio be improved? One option is semi-finished products. The machining rate can be reduced through processes such as near-net shape free-form forging, die forging, precision die forging, and casting. The greatest reduction is achieved through additive manufacturing, as only surface processing is required. Thus, the material removal rates drops to 3 percent. Modern, technology-supported assembly processes can also reduce the CO₂ footprint.

Additive manufacturing as a key technology

Additive manufacturing technologies open up new possibilities for saving material. They enable material-efficient production of complex components with minimal waste. Components can be designed with integrated functions and optimised weight, reducing the number of individual parts and assembly processes. "But if you view such a component through the eyes of a machinist, it really gets scary. There are many free-form surfaces, and the structure is very flexible. There are three critical points in machining these parts: process dynamics in form of chatter, distortion of the part due to high thermal radiation during the laser-based process, and clamping," Dege points out.

Aluminium in aircraft construction

Currently, aluminium still plays an important role in aircraft construction. However, the trend of recent years shows that aluminium is increasingly being replaced by carbon fibre reinforced plastic (CFRP) and titanium. Aluminium still scores primarily due to its recyclability and ease of machining. But whether this will be sufficient in the future remains to be seen.

Source：INTERNATIONAL ALUMINIUM JOURNAL