Metal binder jetting system for the entire additive process chain

• Subject Area: Materials Engineering
• Term: Funded in 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 460825330

Direct-melting metal-based additive manufacturing (AM) processes such as laser powder bed fusion (LPBF) make it possible to produce geometrically complex components, such as topology-optimized grid structures, with high component density and geometric dimensional accuracy. However, low build-up rates and the associated high component costs prevent the broad industrial application, especially in cost-driven industrial areas such as the automotive sector. The necessary increase in productivity of AM can be addressed by the further development of indirect powder bed AM processes such as Metal Binder Jetting (MBJ) with significantly higher build-up rates.The layer-by-layer printing concept of the MBJ developed in the 1990s is comparable to the LPBF process in terms of process sequence. However, instead of a focused laser beam, the MBJ uses a multi-nozzle print head to selectively apply Binder micro-droplets to the powder bed. After the binder application, the powder bed is lowered one layer in the installation space and another layer is applied. The steps powder application, binder application, powder bed lowering are repeated until the component is completely assembled. After the printing process, the powder bed is cured, whereby the liquid components of the binder evaporate. The cured binder-polymer and metal powder form a solid green part, which allows the removal of the uninfiltrated powder. The green body is then sintered in a furnace near the melting temperature. During this process, the binder dissolves thermally. In addition to speed advantages, MBJ sintering offers further advantages over direct AM processes, e.g. in the processing of hard metals or alloys that are difficult to weld.Due to the recent entry of new, established industrial companies such as Hewlett Packard into the MBJ field, there is a clear development compared to the previous possibilities of the MBJ. However, the development of printing and post-processing methods, component design and material development as well as the resulting component performance remain a challenge. This is precisely where the working group applying for funding comes in. On the basis of the new system technology, a significant expansion of the application areas of the MBJ is to be achieved by developing new powder materials, fundamental research into the coordination of the entire production chain, subsequent material/component characterization, as well as by developing predictive load and failure models and, based on this, by working out adapted design rules including shrinkage phenomena. The applicant institutions complement each other thematically in AM, materials development and qualification, powder metallurgy and digital component/process design, in order to be able to comprehensively work on the aforementioned fundamental scientific questions of the MBJ.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Metall Binder Jetting System zur Abbildung der gesamten additiven Prozesskette (inkl. Binder Jetting Anlage und Kammerofen zum Entbindern und Sintern)
• Instrumentation Group: 2110 Formen-, Modellherstellung und gießereitechnische Maschinen
• Applicant Institution: Rheinisch-Westfälische Technische Hochschule Aachen
• Leader: Professor Dr.-Ing. Johannes Henrich Schleifenbaum