High-throughput Direct Energy Deposition (DED-LB\M) for the generation of tailored metallic alloys and composites using in-situ alloying approaches and quasi-simultaneous beam shaping (H-T DED)

• Subject Area: Metallurgical, Thermal and Thermomechanical Treatment of Materials ; Materials in Sintering Processes and Generative Manufacturing Processes ; Production Automation and Assembly Technology
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 434534335

Additive manufacturing technologies, namely Direct Energy Deposition using powder and laser (DED-LB\M), have been investigated at the Institute of Photonic Technologies of the FAU Erlangen-Nürnberg since 2013. In this period, fundamental knowledge about the physical and technical process has been generated. This includes the fabrication of difficult-to-weld material, composite materials (e.g. metal / polymer), and the generation of complex metal alloys by means of in-situ alloying. However, commercially available system technology is restricted due to missing inline process monitoring and limited transferability to large scale components. Therefore, the proposed DED-LB\M concept surpassing state of the art machinery for high-throughput investigations based on a high degree of automation and process monitoring has been developed.For material processing, a 5-axes module with an integrated high power single mode fiber laser system is used. The considered laser system provides the capability of dynamically modulating the beam profile in the order of 50 MHz based on the principle of Coherent Beam Combining. This quasi-simultaneous dynamic beam shaping provides a higher degree of freedom in manipulating process characteristics such as cooling rates, process dynamics and the corresponding mechanical properties, thus enabling the fabrication of alloys which are currently difficult to manufacture. By this, process stability can be improved while also increasing efficiency. The required powder is supplied by a powder feeding unit consisting of four hoppers for in situ alloying and inline sensors for the detection of temporal fluctuations of the single powder streams. The addition of fast powder switchers provide the capability of instantaneously changing the chemical composition of the powder stream.Extensive process monitoring is achieved through several different measurement technologies such as a high speed two color pyrometer, an IR camera based melt pool monitoring system and a Laser Light Section Scanner. The measurement data obtained allow the early identification of suitable process parameters as inappropriate settings would lead to defects in the final part. Information about the local chemical composition of the specimens can be gathered by an integrated Laser Induced Breakdown Spectroscopy (LIBS) system. This setup, consisting of an ns pulsed laser, optics, a CCD camera and a spectrometer, is integrated in a separate process chamber and enables the fast determination of the chemical structure. The transfer of the samples is handled automatically by a 6 axes robot which removes the fabricated sample from the DED-LB\M machine and places it in a cleaning stage before transferring it to the LIBS unit. During LIBS measurement a new substrate is attached to the tilt turn table of the DED-LB\M machine, reducing the temporal delay between the generation of the samples and the subsequent analysis by parallelizing both processes.

• DFG Programme: Major Instrumentation Initiatives
• Major Instrumentation: LMD-Anlage
• Instrumentation Group: 5740 Laser in der Fertigung
• Applicant Institution: Friedrich-Alexander-Universität Erlangen-Nürnberg
• Leader: Professor Dr.-Ing. Michael Schmidt
• Co-Investigators: Professor Dr. Mathias Göken; Professor Dr.-Ing. Tino Hausotte; Professorin Dr.-Ing. Marion Merklein
• Cooperation Partners: Professor Dr. Pavel Krakhmalev; Dr. Sergey Kuryntsev, until 3/2022