3D printed titanium components now onboard the Airbus A350 XWB

Oct. 21, 2014

Laser melting with metals is increasingly gaining in importance in aircraft manufacturing. The reasons for this are typical concerns in the industry however: quicker throughput times, more cost-effective components and heretofore unimaginable freedom of design.

Passenger aircraft remain in use for a very long life cycle of more than 30 years. Planes are exposed to diverse and extremely complex load spectra and extreme temperature fluctuations during ground and flight operations. These include takeoffs and landings, as well as flight operation with permanent turbulence which can lead to several meters of deflection at the wing tips. However, only static load cases are initially relevant to designing retaining structures (brackets).

Airbus A350 XWB

Thanks to additive manufacturing, engineers are able to design parts that are both "lightweight" and "bionics". In terms of aircraft design, future components will be able to absorb specific lines of force yet still be able to fulfill the demands of lightweight construction methods.

Recently, the bracket connector used in the Airbus A350 XWB was honored as a finalist in the running for the "2014 German Industry Innovation Award." The cabin bracket is manufactured using the patented LaserCUSING technology, developed by Lichtenfels, Germany based company Concept Laser GmbH.

The term LaserCUSING, a combination of the C from CONCEPT Laser and the word FUSING (to fully melt) describes the technology: the fusing process generates components layer by layer using 3D CAD data. The method allows the production of complex component geometries without tools to create parts that are difficult or even impossible to achieve through conventional manufacturing.

Cabin bracket for the Airbus A350 XWB made of Ti

In the eyes of the jury, this cross-industry project is revolutionizing the way structural aircraft components are made and lightweight construction is implemented in civil aircraft. Previously this component was a milled part made of aluminum (Al); now it is a printed part made of titanium (Ti) with a weight reduction of greater than 30%.

Lightweight construction approach

The "lightweight construction" approach is intended to help airlines operate their aircraft more economically. For retaining elements (brackets), the achievable weight reduction results in a tendency towards lower fuel consumption or the potential to increase the load capacity of aircraft.

A new aircraft design requires thousands of Flight Test Installation (FTI) brackets, which are produced in very small unit quantities. Laser melting of metals allows designers to come up with new structures. The additive components are in fact more than 30% lighter than conventional cast or machined parts. In addition, the CAD data are the direct basis for an additive construction job. The omission of tools reduces the costs and shortens the time until the component is available for use by up to 75%.

In addition, it's now possible at an early stage to produce functional samples of components that are similar to series produced components. This means that sources of error can be identified in the early stages of the design process, which allows for optimization of processes within the project as a whole.

Peter Sander, Head of Emerging Technologies & Concepts, Airbus, Hamburg: "Previously we budgeted around six months to develop a component – now, it's down to one month."

Peter Sander, Airbus

"Green technology"

Milling of aircraft parts results in up to 95% recyclable waste. With laser melting, the user receives components with "near-final contours," and the process produces only around 5% waste.

"In aircraft manufacturing, we work with the "buy to fly" ratio, and 90% is a fantastic figure. Of course, this value is also reflected in the positive energy balance," said Prof. Dr.-Ing. Claus Emmelmann, CEO, Laser Zentrum Nord GmbH, Hamburg.

This makes the process especially attractive when valuable and expensive aircraft materials, such as titanium, are being used.

Frank Herzog, CEO & President, Concept Laser GmbH, Lichtenfels: "LaserCUSING is a green technology and improves the often discussed environmental footprint of production."

Aircraft construction as an engine of change

Generally speaking, laser melting results in a positive effect on manufacturing costs for small to medium-sized unit quantities.

Peter Sander: "Batch size considerations are more essential in aircraft construction than in volume manufacturing in order to achieve economies of scale." Laser additive manufacturing not only eliminates costs for tools, but also offers greater design freedom than conventional manufacturing strategies. Previously unimaginable geometries can be combined with functionalities for the first time. The flow of forces in the component can already be determined very accurately in the CAD design.

"Inline Process Monitoring" with the QMmeltpool QM module: The system uses a camera and photo diode to monitor the process within a very small area of 1x1 mm². The process is then documented.

This way undercuts and interior channels, e.g. for cooling, can be produced. Prof. Dr.-Ing. Emmelmann: "I see great potential in particular for structural components with dimensions of up to one meter, as well as for engine components."

Prof. Dr.-Ing. Claus Emmelmann, Laser Zentrum Nord

In addition, laser melting technology is capable of developing safety-related components that are more durable than the components available today. Prof. Dr.-Ing. Emmelmann explained: "Materials produced using laser additive manufacturing have greater rigidity while at the same time, less ductility; this can be enhanced with the right heat treatment, however."

Spare parts supply 2.0: Timely, decentralized and "on demand"

In the future it will be possible to manufacture spare parts in "on demand" in decentralized locations and without the need for tools. In the event of a component failure, the spare part can be produced directly where it is needed. A reduced capital commitment increases flexibility and especially the time needed to obtain safety-related components. This is especially attractive given the cost pressures in the aviation industry.

Decentralized production networks may be formed and global and regional strategies are possible. This minimizes transport distances and above all, delivery times. As a consequence, maintenance-related downtimes and inspection times for aircraft are reduced.

Bionics in component or product design

Laser melting with metals allows extremely fine, even bone-like, i.e. porous structures to be produced. "Future aircraft parts will therefore have a "bionic" look", Prof. Dr.-Ing. Emmelmann believes.

Over millions of years Nature has produced optimized functional and lightweight construction principles which minimize the amount of resources required in clever ways. Airbus is currently analyzing solutions found in nature with regard to their applicability.

By relying on "intelligent exposure strategies" of the laser, it can apply layers to a component in a strategic manner in order to produce custom properties in terms of structure, rigidity and surface quality. Peter Sander: "The first prototypes show the great potential of a bionically-motivated approach involving all relevant safety requirements. The process is expected to launch something of a paradigm shift in design and production."

Posted in 3D Printing Technology

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