Investigation of the combined process chain based on SLM and LMD

• Applicants: Professor Dr.-Ing. Michael Rethmeier; Professor Dr.-Ing. Eckart Uhlmann
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: from 2017 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 378970463

Additive manufacturing (AM) has become more important in recent years with applications in Rapid Prototyping, Rapid Tooling and Rapid Manufacturing. This leads to shorter product development times as well as shorter manufacturing times. AM offers tremendous advantages such as free geometric design as well feature-integration, e.g. cooling channels or lightweight structures. With the current state of the art, it is not possible to produce complex and fine structures while achieving high build rates at the same time. Powder based applications such as selective laser melting (SLM) allow the build-up of very complex structures. However, due to low build speed it is often not economically viable in series or mass production. In addition, the maximum size of the components is limited by the size of the process chamber. Due to the material position in a powder bed, a combination of different materials at selected locations is not yet possible. In contrast, laser metal deposition (LMD) is an additive technology with high build rates. The part size is not limited and a change of materials is easily implemented. However, the process can only build rough structures. A combined process chain of SLM and LMD offers great potential to combine the advantages of the individual methods.The aim of this project is to understand the fundamentals and effects in the process chain SLM-LMD. Increased functionality of additive manufactured parts is a result of these investigations. In this combined process chain, SLM is used for the production of complex structures. LMD is responsible for the production of the massive and bigger geometries. The flexible material change in process offers additional opportunities to extend the functionality of the process chain. For a basic understanding of the process combination, an investigation is necessary to determine the extent in which SLM structures are affected by the following LMD material application, and what effects and properties occur in the connection zone as well in the entire specimen. Finally, empirical models for selected functional properties will be derived from the technological studies for both processes. The results should provide a knowledge base for further applications of the combined additive process chain. Inconel 718 will be used as a basic material for the whole project, due to the high corrosion resistance, excellent high-temperature properties and relevance for components in turbine production.

• DFG Programme: Research Grants