Selective Electron Beam Melting (SEBM) is one of the most promising additive manufacturing technologies for producing high-performance materials, owing to its fast control of the beam position, high power output and energy absorbance as well as low oxidation and contamination risk. Nevertheless, the so-called smoke phenomenon, which results in an explosion-like powder spreading within the whole machine, restricts the further development of SEBM of different materials. So far, methods to prevent smoke event are mainly based on trial-and-error optimization and empirical rules. A basic understanding of powder smoking mechanism is highly desired to exploit the potential of the SEBM process. According to experimental observations at the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) and at the TsingHua-University (THU), the proposed project is based on the novel hypothesis that powder smoking is initiated by gas evaporation, which can take place at relatively low temperatures under vacuum conditions, followed by an avalanche effect caused by electrostatic charging of the powder bed during SEBM. At FAU, the research focus will lie on the investigation of the effect of gas evaporation, while THU will be committed to discover the influence of powder bed charging during SEBM. Main objectives of the project are to in situ observe the evolution of the whole smoking process and to establish a physical model to explain the smoking mechanism as well as to prevent the powder smoking. First, far-field and near-field ELectron-Optical (ELO) observation system as well as other different process monitoring tools will be used for the in situ observation of smoking at FAU and THU, respectively. Second, in order to evaluate key factors leading to smoking, the effect of powder properties (at FAU) and process parameters (at THU) will be investigated. Third, for physical modelling, recoil pressure induced by gas evaporation (at FAU) and electrostatic repulsive forces caused by powder bed charging (at THU) will be taken into account. Finally, optimized scan strategies and requirements on powder properties can be derived to increase process stability and to allow the use of finer powders. In addition, by analyzing ELO signals a real-time signal processing system will be developed, so that the SEBM process can be promptly interrupted at the initial stage of powder smoking, before the avalanche effect (catastrophic smoke event) occurs.
Research projects
Current projects
Grundlagenuntersuchung zum Pulversmoke-Phänomen beim selektiven Elektronenstrahlschmelzen
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Selective Electron Beam Melting (SEBM) is one of the most promising additive manufacturing technologies for producing high-performance materials, owing to its fast control of the beam position, high power output and energy absorbance as well as low oxidation and contamination risk. Nevertheless, the so-called smoke phenomenon, which results in an explosion-like powder spreading within the whole machine, restricts the further development of SEBM of different materials. So far, methods to prevent smoke event are mainly based on trial-and-error optimization and empirical rules. A basic understanding of powder smoking mechanism is highly desired to exploit the potential of the SEBM process. According to experimental observations at the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) and at the TsingHua-University (THU), the proposed project is based on the novel hypothesis that powder smoking is initiated by gas evaporation, which can take place at relatively low temperatures under vacuum conditions, followed by an avalanche effect caused by electrostatic charging of the powder bed during SEBM. At FAU, the research focus will lie on the investigation of the effect of gas evaporation, while THU will be committed to discover the influence of powder bed charging during SEBM. Main objectives of the project are to in situ observe the evolution of the whole smoking process and to establish a physical model to explain the smoking mechanism as well as to prevent the powder smoking. First, far-field and near-field ELectron-Optical (ELO) observation system as well as other different process monitoring tools will be used for the in situ observation of smoking at FAU and THU, respectively. Second, in order to evaluate key factors leading to smoking, the effect of powder properties (at FAU) and process parameters (at THU) will be investigated. Third, for physical modelling, recoil pressure induced by gas evaporation (at FAU) and electrostatic repulsive forces caused by powder bed charging (at THU) will be taken into account. Finally, optimized scan strategies and requirements on powder properties can be derived to increase process stability and to allow the use of finer powders. In addition, by analyzing ELO signals a real-time signal processing system will be developed, so that the SEBM process can be promptly interrupted at the initial stage of powder smoking, before the avalanche effect (catastrophic smoke event) occurs.
Simulation methods for additive processing of high temperature alloys - microstructure, in-service properties and repair
(Third Party Funds Single)
Funding source: Bundesministerium für Wirtschaft und Technologie (BMWi)
Development of a new type of rotor and other motor components made of aluminum alloys for linear motors through the use of cast aluminum components to increase the maximum motor power by 30%
(Third Party Funds Single)
Funding source: Bundesministerium für Wirtschaft und Technologie (BMWi)
Intelligent catalyst carrier concept with additively manufactured structures made of shape memory alloys for the optimization of the wall heat transfer in tubular reactors
(Third Party Funds Single)
Funding source: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Real-time study of electron beam melting of metals
(Third Party Funds Single)
Funding source: Bundesministerium für Bildung und Forschung (BMBF)
Mesoscopic modelling and simulation of properties of additively manufactured metallic parts (C5)
(Third Party Funds Group – Sub project)
Term: 1. July 2019 - 30. June 2023
Funding source: DFG - Sonderforschungsbereiche
URL: https://www.crc814.research.fau.eu/projekte/c-bauteile/teilprojekt-c5/
Based on the gained knowledge of projects B4 and C5,the aim of this project is to account for the influence of part borders on theresulting material/part-mesostructure for powder- and beam-based additivemanufacturing technologies of metals and to model the resulting meso- andmacroscopic mechanical properties. The mechanical behavior of thesemesostructures and the influence of the inevitable process-based geometricaluncertainties is modelled, verified, quantified and validated especially forcellular grid-based structures.
Additive manufacturing of single crystalline superalloys
(Third Party Funds Group – Sub project)
Term: 1. January 2012 - 31. December 2023
Funding source: DFG / Sonderforschungsbereich / Transregio (SFB / TRR)
URL: http://www.sfb-transregio103.de/
Project B2 explores selective electron beam melting, which belongs to the additive manufacturing technologies, for the processing of single-crystalline superalloys. Especially the potential of the inherent high cooling rates is investigated. These lead to an ultra-fine and directional solidified microstructure. The main challenge of this project is to develop innovative processing strategies based on a sound theoretical process understanding in order to produce crack-free and preferably single crystalline samples, also with higher geometric complexity.
Supply of single crystalline Ni- and Co-base superalloys: planning, melting, casting and characterization
(Third Party Funds Group – Sub project)
Term: 1. January 2012 - 31. December 2023
Funding source: DFG / Sonderforschungsbereich / Transregio (SFB / TRR)
URL: http://www.sfb-transregio103.de/
The scientific service project of SFB/Transregio 103 takes care of the procurement and processing of all project materials.
Single crystalline solidification with enhanced microstructure
(Third Party Funds Group – Sub project)
Term: 1. January 2012 - 31. December 2023
Funding source: DFG / Sonderforschungsbereich / Transregio (SFB / TRR)
URL: http://www.sfb-transregio103.de/
Project B1 focuses on the investigation of the newly developed FCBC (Fluidized Carbon Bed Cooling) process for the single crystalline solidification of superalloys. In comparison with commercially available investment casting processes it could be shown that FCBC benefits from a higher cooling potential. In combination with a dynamic baffle a higher axial temperature gradient will evolve. Objective of the upcoming project period is the improvement of the process understanding as well as the process optimization, carried out on a 10 kg prototype plant. A further point of interest is the exploitation of the increased microstructural homogeneity for alloy development.
Process strategies for selective electron beam melting (B2)
(Third Party Funds Group – Sub project)
Term: 1. July 2011 - 30. June 2023
Funding source: DFG / Sonderforschungsbereich (SFB)
URL: https://www.crc814.research.fau.eu
Selective electron beam melting represents an interesting alternative to laser melting in the field of powder-based additive manufacturing methods. The evacuated build chamber and the overall high performance allow for the production of components with excellent properties. The almost inertia free deflection and focusing of the electron beam by electromagnetic lenses facilitates extremely high construction speeds at very high precision levels.
This project has the goal to optimize electron beam properties and to provide a better understanding of the melting process and of other influences in order to tap the full potential of this process, both with regard to energy input and process speed. Here, process monitoring plays an important role. Process influences, such as temperature distribution, scanning strategies, and electron beam properties are investigated using both a thermal and a high-speed camera. In addition, the existing field of parameters will be expanded to include high scanning rates (up to 10 m/s). The influence of powder properties, e.g., particle size distribution and bulk density, different scanning strategies, e.g., the multi-beam strategy, will be evaluated in order to tailor component properties.
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