3D printed titanium components on Airbus

Laser melting with metals gains importance in aircraft manufacturing: quicker throughput times, more cost-effective components and heretofore unimaginable freedom of design are often-cited advantages of this technology. However, a range of new benefits are now becoming apparent, such as lightweight construction, bionics and a new approach to design.

Previously the component was a milled part made of aluminium (Al); now it is a printed part made of titanium (Ti). Naturally it is significantly lighter than it used to be. Peter Sander, Head of Emerging Technologies & Concepts, Airbus in Hamburg expressed what he believes about the change in manufacturing strategy mean for aircraft manufacturing in the future, in terms of prospects and technology? 

Recently we have been hearing about "composite aircraft" and now additive manufacturing technologies. How does this change the design of structural elements used in aircraft?

Peter Sander: Our primary objective is to reduce weight. This approach helps our customers, the airlines, operate their aircraft more economically. Additive layer manufacturing or laser melting with metals, also known simply as 3D printing, allows us to design completely new structures. They are actually more than 30% lighter than conventional designs realized using casting or milling processes. Another factor is that we can proceed directly from 3D designs to the printer, that is, the laser melting system. Usually tools are required to manufacture aircraft parts – this is now no longer the case for us. This saves money and shortens the time until the component is available for use by up to 75%. To cite an impressive statistic: previously we budgeted around six months to develop a component – now, it's down to one month.

What are some of the effects that result from transitioning from milled or cast components to printed components?

Peter Sander: Milling of aircraft parts in particular results in up to 95% recyclable waste. With laser melting, we produce components with "near-final contours”, which are associated with waste of only around 5%. This makes the process especially attractive when valuable and expensive aircraft materials, such as titanium, are being used. Compared to casting, we have the additional advantage of not requiring any foundry tools. This is tangibly reflected in saved time and improved cost structures. Furthermore, additional safety considerations are associated with cast parts, such as cavities. Last but not least, they are heavier than printed components.

What potential applications do 3D printing techniques offer for aircraft manufacturing and structural elements used in aircraft?

Peter Sander: Two areas need to be considered in this connection: process optimization, on one hand and product design, on the other. For us, process optimization means that we no longer require any foundry, injection moulding or pre-production tools. We can print components directly from the 3D design system. This reduces our throughput time by up to 75%, with considerably lower one-off expenses. It's easy to imagine how attractive this is for us, especially for series with few and very few units. Lot size considerations are more significant in aircraft manufacturing than for high-volume production, as is familiar in the automotive and consumer sectors. 

For example, we installed several tons of test equipment in the first test aircraft. This required thousands of Flight Test Installation (FTI) brackets, to be produced in very small unit quantities. Spare parts are an additional, exciting area. In the future we will be able to manufacture them close to where they're needed, without tools and on an "on demand" basis – instead of having to finance large warehouses to store rarely needed spare parts all around the world. This reduces capital commitment while providing huge flexibility. 

And now, regarding the second point, component or product design: since with laser melting we can manufacture very fine – even bone-like – porous structures, the aircraft parts of the future will look "bionic”. Nature has optimized functional and lightweight construction principles over millions of years, minimizing the amount of resources required in clever ways. We are currently investigating and analysing these solutions found in nature with regard to their applicability. Initial prototypes indicate great potential in this approach. The process is expected to launch a sort of paradigm shift in design and production.

Nevertheless, at what point does the technology reach its limits for safety-relevant components? 

Peter Sander: Generally speaking, there are no compromises in aircraft construction, since safety is the prime concern. Especially when one considers that our products remain in the skies for up to 30 years. When it comes to metals in aircraft construction, welding is the most common process. Aircraft manufacturers have long been familiar with it. From experience, we know how welded components must be handled to satisfy the high safety requirements. However, we still have to learn how best to take advantage of implementing the new geometrical freedom in component design. Toward that end, we will have to perform many structural tests and trials over the coming years. The result will be a novel "bionic" aircraft design, I'm sure of it.

What methods or instruments do you use to monitor and/or validate processes with the LaserCUSING?

Peter Sander: As an aircraft manufacturer, monitoring during the component's construction phase is one of the most important aspects for industrial applications. In practice, the "Inline Process Monitoring" provided by the QMmeltpool QM Module from Concept Laser means that 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.

Does the additive manufacturing approach change the thinking around design in aircraft manufacturing? If yes, how is this evident?

Peter Sander: To me, the "freedom of design" stands out: the degree of design freedom with which we can determine the force distribution in the component with great precision at the Laser Zentrum Nord thanks to CAD design. The next generation of aircraft engineers will understand 3D printing and all the opportunities it brings in greater depth. Thinking around design and production is currently changing. 

We should also remember that resistance to new things is only slowly overcome. Our production engineers are currently well-trained in casting and milling, so we need new insight and experience. Last but not least, some advocacy work has to be done in the form of practical examples we can point to in aircraft manufacturing. In general, laser melting technology is capable of developing safety-related components that are even better, lighter and more durable than the components available today.

What general changes have 3D strategies produced in aircraft manufacturing, in your opinion?

Peter Sander: Initial studies show that the number of manufacturing steps necessary has been cut in half, since the process yields blanks with near-final contours. Welded components composed of multiple parts are also attractive, as they can now be manufactured "in a single process" without welding equipment. 

Additive 3D printing is enabling new, more rapid speeds for component development and the construction process, drastically shortening previous development timelines. The cost structure of our projects is also changing significantly. The new approach has also allowed lightweight construction to develop further. And it is leading to new design perspectives, which will be evident in the different geometries used.

What opportunities do you see for integrating various functions, such as cooling functions, into the components of the future?

Peter Sander: Similar to aircraft structures, we are currently rethinking the entirety of aircraft systems. We are facing a new continent of opportunities and options, so to speak. We need maps of the unknown terrain before us, as it were; in other words, experience and production strategies. We already have all of that for conventional processes. But here we are entering new territory, one with fascinating opportunities on the horizon. Initial prototypes produced in our development work show significant potential in terms of reducing costs and weight. Functional integration is one of the possible new options. I am convinced that we will make good progress toward producing safety-related components in better and more cost-effective ways.

What components produced using additive manufacturing are conceivable in aircraft manufacturing over the next decade?

Peter Sander: If development continues in a similar manner, I see no technical restrictions. The decision will then ultimately be based on cost-effectiveness and on the industrial availability of metal powders and high-speed machines.