Additive manufacturing learns about superalloys
To achieve their goal of faster, more versatile additive manufacturing with new superalloys, engineers must first improve the current industrial 3D printers so that these machines can also process very strong and extremely heat-resistant alloys. The researchers are drawing on their experience with laser powder deposition welding and using artificial intelligence (AI). They contribute their materials expertise to the Fraunhofer “futureAM” joint project. The aim of the partners is to make additive production systems for metal components 10 times faster and also to cope with superalloys.
In order to be able to use more materials in additive manufacturing, the engineers at the Fraunhofer IWS have refined laser powder deposition welding over many years. In this process, a system transports various filler powders into a process zone. There, a laser melts the powder and welds it onto a workpiece surface. This produces the desired shape layer by layer. One of the advantages of this process is that the process can be very flexibly adapted to the requirements of high-performance materials. This makes it 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, powder types, delivery rate and other settings are correct. As part of the Fraunhofer lead project “futureAM – Next Generation Additive Manufacturing”, Fraunhofer IWS engineers are recording numerous sensor data with very high sampling rates for this purpose.
However, this generates very large amounts of data that are difficult for people to understand. In order to nevertheless find hidden connections in these signal floods, the experts use methods of artificial intelligence (AI) and machine learning, which is also being researched at the Fraunhofer IWS. Over time, the machines learn to make decisions independently. For example, they can see for themselves whether a slight rise in temperature in the welding process can be tolerated or whether they have to take immediate countermeasures.
“The industry is looking for ever more and ever different materials that are often difficult to process,” emphasizes Prof. Frank Brückner, Business Unit Manager Generation and Printing at the Fraunhofer IWS. One example of this is aircraft engines: they could work hotter and more efficiently if the materials could withstand temperatures of around 1200 degrees and more. Although there are materials that can withstand such high temperatures, they are more expensive and difficult to process using traditional methods. Additive manufacturing is intended to solve this dilemma. Using laser powder deposition welding, we can bring different powders into the process zone simultaneously or successively with precisely adjustable feed rates,” explains Michael Müller. Designing an entire component from a single material is not very effective because the component is not exposed to the same heat at all points. “It would be better to use the expensive, highly stressable material only where it gets really hot,” says project administrator Michael Müller from Fraunhofer IWS.
In other places, a cheaper material would be sufficient. This is precisely what can be achieved with additive production systems – once they have learned to process the required superalloys. “In the next step, we want to combine various high-performance materials within a single component,” announces project administrator Müller. In the futureAM joint project, the IWS and five other Fraunhofer Institutes are bringing this and other know-how together to take additive manufacturing to a new level. By summer 2020, they want to integrate all this expertise into the additive manufacturing process chain and demonstrate it on tangible components.