Oerlikon, a global technology group, entered into a research partnership with Linde, an industrial gases company, and the Technical University of Munich (TUM), one of the leading German universities in engineering. The aim of the EUR 1.7 million project is to conduct additive manufacturing (AM) research with the aim of developing new high-strength, lightweight aluminum-based alloys that can serve the safety and weight reduction needs of the aerospace and automotive industries. The Bavarian Ministry of Economic Affairs is providing 50% of the required funding for the project.
This research partnership was born out of an AM collaborative announced in early October, in which GE Additive, Oerlikon, Linde, and TUM established of a Bavarian additive manufacturing cluster and an Additive Manufacturing Institute. The aim of the new cluster and institute is to promote higher levels of collaboration and cross-disciplinary research amongst the companies and the university. Having a wide variety of expertise in one geography is expected to accelerate advances in AM.
Addressing the challenges of Aluminum AM
Producing the optimum aluminum alloy with a high content of lightweight elements like magnesium through an AM process requires a deep understanding of chemistry, thermo-, and fluid dynamics. During the manufacturing process, the metal powder is applied one layer at a time on a build plate and melted using a laser beam. This fuses the metal powder together and forms the desired complex, three-dimensional geometries. The process takes place in a well-defined shielding gas atmosphere.
“There are significant challenges during the AM of aluminum alloys because the temperatures reached in the melt pool create an extreme environment that leads to evaporation losses of alloying elements that have comparatively low boiling temperatures — such as magnesium,” said Dr. Marcus Giglmaier, project manager for the Additive Manufacturing Institute and research funding manager. “Additionally, the cooling rates of more than 1 million °C per second, create high stresses during the solidification process, which can cause micro cracks in the solid material.”
The project draws on the high-tech expertise of each of the three members. Oerlikon’s expertise in powder and material science will contribute to the development of the novel material. “Using our proprietary software, Scoperta-RAD, which enables big data simulation and analysis, Oerlikon provides critical solutions for the development of new materials and performance optimization of available materials,” noted Dr. Alper Evirgen, metallurgist at Oerlikon AM.
Linde’s technology and expertise in gas atmosphere control and evaporation suppression during the AM process – including the processing of aluminum-based alloys – overcomes impurities within the print chamber. This will help manufacturers achieve optimal 3D-printing conditions. “Characterizing and controlling the gas process during AM not only has the potential to prevent evaporation losses, but also to accelerate the entire printing process,” explained Thomas Ammann, expert in AM at Linde. “Using a tailor-made gas chemistry for the new alloy would help to control the processes occurring in the melt pool and minimize the compositional changes of the alloys, as well as preventing cracking during printing.”
For its part, the Institute of Aerodynamics and Fluid Mechanics (AER) at TUM will be able to provide a detailed understanding of the physical phenomena taking place during the AM process using numerical simulations. “The AM research alliance bridges the gap between our latest numerical modeling achievements and future industrial applications,” said Prof. Nikolaus Adams, director of the AER.
At AER, a process simulation tool has been developed to cover the whole melt pool dynamics – from solid to liquid and gas with phase change models, surface-tension effects and thermal transport. Regarding the benefits of computational fluid dynamics, Dr. Stefan Adami at TUM, stated, “A detailed insight into the simultaneously occurring thermo-fluid dynamic phenomena is crucial in gaining a better understanding of the entire process and the final material characteristics.”