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Item type:Publication, Access status: without files , Industrialization of additive manufacturing(Wiley, 2025-01-13); ; ; ; Jankowiak, MircoOur world is constantly facing a wide variety of social challenges – currently, issues such as climate change, security, demographic change, and resource conservation are of significant importance and show an acute need for action. Disruptive technologies, among other things, are needed to tackle such problems. Additive manufacturing (AM) is regarded as the ‘game changer / paradigm shift’ technology for the digital, automated production of the future – as the key enabler of ‘Production 2.0’.Publicationtype: Journal Article16 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Signal processing of airborne acoustic emissions from laser metal deposited structuresLaser Metal Deposition (LMD) is an additive manufacturing process that enables the production of complex structures on existing parts. To reduce the use of costly and energy-intensive produced materials like titanium, these structures can be selectively deposited on favorable but differing substrate materials. However due to differing material characteristics, this results in a high defect potential. Extensive process parameter development and online process monitoring helps to minimize the impact of defect formation. Monitoring of airborne acoustic process emissions can be used to identify critical defects early during the process and gain information about process stability. Two approaches for in-process time-frequency monitoring of the acquired acoustic data were compared within this work: The short time Fast Fourier Transformation and the Continuous Wavelet Transformation. Performance criteria based on detected distinct defect events were defined to evaluate both approaches and define specifications for an Acoustic Emission In-Process Monitoring system.Publicationtype: Journal Article34 247 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Laser metal deposition of titanium parts with increased productivity(2018-08-02); ; ; Laser Metal Deposition (LMD), an additive manufacturing technique, is described here as an alternate for conventional manufacturing process to build aerospace components. Traditional milling of thin-walled, ribbed-, lightweight, high-valued Titanium structures generate machining wastes as high as 95%. This paper presents an LMD system setup along with an adapted manufacturing process chain for fabrication of near-net shaped Ti-6Al-4V components. Demonstrator parts built using the system setup are then shown.Publicationtype: Book Part451 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , From powder to solid: The material evolution of Ti-6Al-4V during laser metal depositionLaser metal deposition (LMD) offers an alternative to conventional machining of titanium aviation parts, because near net shape parts can be produced with high deposition rates. In this paper the material evolution of Ti-6Al-4V during LMD is investigated. Powder properties as well as the microstructure in deposited structures are described and analyzed. At first, the influence of powder particle size on the process is quantified by creating two powder fractions with different sieving procedures. The used material is recycled Ti-6Al-4V powder from a powder bed-based AM process with particle sizes up to 150 µm. The powder is characterized according to current standards; apparent density, tap density and the flowability are determined as well as the particle size distribution. Additionally, the particle morphology is analyzed using electron beam microscopy. In order to link the powder properties to the LMD process and to identify impact factors to the feeding behavior the mass flow of both powder fractions is measured. Secondly, walls are manufactured with the characterized powder and the resulting microstructure is analyzed. Because of the layer-wise deposition and the resultant periodic heat input each layer experiences several thermal cycles. The thermal boundary conditions change with increasing wall height. The occurring solid phase transformation result in a heterogeneous microstructure with non-equilibrium phases (martensitic or massive α) and α+β lamellae. Based on an existing numerical model the thermal history of each layer is estimated and an explanation is presented for the complex sequence of solid phase transformations in each area of the structure.Publicationtype: Conference Paper193 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Characterization of the anisotropic properties for laser metal deposited Ti-6Al-4 V(2017-05-01); ; ; ; Laser metal deposition (LMD) connected with milling processes offers the opportunity for an efficient, resource conserving manufacturing for large structural components made from Ti-6Al-4 V. Conventional manufacturing routes for example in the aerospace industry come along with up to 95% of the waste material that has to be machined from the bulk material. LMD is an additive manufacturing process building parts based on nozzle-fed powder by laser solidification. This technology offers unique advantages for the production of near net-shape parts. In contrast to the powder bed-based technologies, it also provides a higher productivity rate. Today, LMD lacks reproducible process strategies manufacturing large parts in narrow tolerances and predictable microstructural properties. The building height of a single layer and the geometrical shape of a three-dimensional shaped part alter progressively with increasing part dimensions, consecutively leading to a higher effort in the manufacturing-process development for such parts. To reduce this effort, in this paper, first the actual state of the anisotropic properties is investigated for LMD-manufactured parts to obtain thorough knowledge of the process and shape-related dependencies with the quality aims. A preliminary experimental investigation of the shape and process-dependent properties such as the microstructure (chemistry changes and grain sizes), mechanical properties (hardness), and geometry (tolerances) is conducted. Based on these results, an in-depth study with optimized parameter sets is carried out to identify the linkage between geometry, process parameters, and the quality criteria of the part, using methods such as light microscopy, inductively coupled plasma-mass spectrometry, Vickers hardness, coordinate measuring, and laser scanning microscopy. For this purpose, representative shaped specimens are manufactured with the LMD-process through different optimized process strategies. The results give the opportunity to evaluate the impact of process parameter changes and the shape on the part quality such as mechanical properties, surface quality, and element loss. This is achieved through identifying the relationship between the input and the output factors from the experimental study, and their importance for part quality is assessed. It is shown that the complex correlation between the process parameters, the part geometry, and the resulting quality can be controlled with suitable process design in LMD-manufacturing of Ti-6Al-4 V parts. Finally, based on the summarized results, an outlook is given on tolerances for different quality aims.Publicationtype: Journal Article153