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Fraunhofer IWS discovering superalloys, new AM processes

24 May 2019

Aim of German researchers is to speed up AM systems for components; project futureAM accelerating process by factor of 10.

Scientists at the Fraunhofer Institute for Material and Beam Technology (IWS) in Dresden, Germany, have developed innovative methods enabling more types of materials to be processed in additive manufacturing systems.

For example, additive manufacturing systems could facilitate better future aircraft engines with lower fuel consumption using novel designs and lighter, stronger “super alloys”. However, engineers must first improve the current industrial 3D printers in such a way that these machines can also process very strong and extremely heat-resistant alloys.

The researchers have used their significant experience with laser powder buildup welding technologies and added artificial intelligence. They are contributing their materials expertise to the ongoing Fraunhofer joint project futureAM (see below). The aim of the project partners is to speed up additive manufacturing systems for metal components by a factor ten and also to manage superalloys.

IWS engineers have refined laser powder buildup welding over decades in order to allow more materials to be applied in additive manufacturing. In this procedure, a system feeds various filler powders into a process zone. In that, a laser melts the powder and deposits it on a workpiece surface. As a result, the desired part is generated in a layer by layer process.

"One of the advantages of this additive procedure is that we can adapt the process very flexibly to the requirements of high- performance materials," said Fraunhofer IWS project administrator Michael Müller. In this way it is also possible, for example, to print nickel-based alloys that are difficult to weld and process using traditional methods. However, this only works if the temperature, powders, feed rate and other parameters are correct.

"We have to adjust all the set screws precisely," said Müller. "This is the only way we can find the right recipe." Within the framework of the Fraunhofer lighthouse project futureAM Next Generation Additive Manufacturing, IWS engineers are recording numerous sensor data with high sampling rates for this purpose. However, this generates large amounts of data that can be difficult to understand.

AI learns to decide

Nevertheless, the Fraunhofer team is using advanced methods of artificial intelligence and machine learning in a working group led by Prof. Karol Kozak, Head of Image Processing and Data Management at IWS, to find hidden connections in these signal floods. Special analysis algorithms can link the measured sensor values with the institute's powder database and evaluate further process parameters. Thus, the machines can learn to make their own decisions.

For example, they can determine for themselves whether a slight rise in temperature in the welding process can be tolerated or whether they have to take immediate remedial action before the entire component is wasted. "Industry is looking for more and different materials which are often difficult to process," said Prof Frank Brückner, Business Unit Manager Generation & Printing at Fraunhofer IWS.

Aircraft engines

Aircraft engines mentioned above are examples illustrating this prospect: they could work more efficiently and at higher temperatures – if most materials did not already fail at temperatures of around 1200 degC. There are materials that can withstand such high temperatures, but they are very cost-intensive and difficult to process using traditional methods.

Additive manufacturing is intended to solve this problem. Moreover, it could help to achieve a more cost-effective design: "Using laser powder buildup welding, we can feed different powders into the process zone simultaneously or successively with precisely adjustable feed rates," said Prof Brückner .

Designing an entire component out of a singular material is not very effective since the component is not exposed to the same heat at all points." Preferably, the expensive, highly resistant material should only be used where it gets really hot," said Müller. "In other areas, a less expensive material will be sufficient." This is precisely what can be achieved with additive manufacturing systems – once they have learned to process the required superalloy.

futureAM develops additive manufacturing

In the "futureAM" joint project, the IWS and five other Fraunhofer Institutes are pooling this technology and further expertise to push additive manufacturing to a new level. By summer 2020, they want to integrate all their expertise into the additive manufacturing process chain and demonstrate it on realistic components.

In November 2017, the Fraunhofer lighthouse project futureAM was launched with the aim of accelerating additive manufacturing of metal components by at least a factor of ten. The focus is on a holistic view of digital and physical added value from incoming order to the finished metal 3D printing component.

The central goal is a leap into a new technology generation of additive manufacturing. Five other Fraunhofer institutes are participating in this project under the leadership of the Fraunhofer ILT: IWS, IWU, IAPT, IGD and IFAM. Fraunhofer IWS will be exhibiting at LASER World of PHOTONICS in Munich, Germany, June 24-27th.

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