Dr.-Ing.

Day, Robin

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Now showing 1 - 7 of 7
  • Publication
    Compensation of structure distortion in nonisothermalhot forming of laser structured thin glass
    ( 2024-06-12)
    Kohse, Martin orcid-logo
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    Meiners, Constantin
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    Plakhotnik, Denys
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    Vogel, Paul-Alexander
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    Day, Robin
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    Grunwald, Tim
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    Bergs, Thomas
    The modern automotive industry employs various complex shaped glass components. Around 50% of these components are currently functionalized using environmentally and economically unfriendly etching or replication processes. We present a new approach of direct laser structuring on glass, which reduces costs and energy by up to 60% and avoids harmful chemicals, offering a more sustainable alternative to conventional processes.
  • Publication
    Assessing the Environmental and Economic Impact of Wire Arc Additive Manufacturing
    ( 2024-04-25)
    Derra, Thomas orcid-logo
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    Belghith, Khouloud
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    Gräfe, Stefan
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    Day, Robin
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    Bergs, Thomas
    Additive Manufacturing (AM) has continuously been integrated in the modern production landscape and complements traditional manufacturing processes by allowing the creation of complex three-dimensional objects through layer-by-layer material deposition. Especially with new design opportunities and short lead times it has significant impact on different industrial sectors such as healthcare, automotive and aerospace. Compared to other AM technologies, Wire Arc Additive Manufacturing (WAAM) has a particularly high material deposition rate and a high degree of flexibility when building large components. Therefore, WAAM has great potential for efficient and resilient production. To quantify this potential the environmental and economic impact must be assessed. The presented study focuses Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) and presents a general methodology for impact analysis as well as a transfer to WAAM. The methodology consists of four steps in accordance with ISO 14044:2006: goal and scope definition, inventory analysis (environmental/economic), environmental impact assessment/cost aggregation, interpretation. For the transfer to WAAM a cradle-to-gate analysis is conducted. The relevant process chain leads from alloy production to the WAAM product manufacturing. The methodology generates relative data, so the final assessment of WAAM must be set into context with alternative processes.
  • Publication
    Initial experiments to regenerate the surface of plasma-facing components by wire-based laser metal deposition
    ( 2024)
    Tweer, Jannik
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    Day, Robin
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    Derra, Thomas orcid-logo
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    Dorow-Gerspach, Daniel
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    Loewenhoff, Thorsten
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    Wirtz, Marius
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    Linsmeier, Christian
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    Bergs, Thomas
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    Natour, Ghaleb
    Plasma-facing components (PFC) in nuclear fusion reactors are exposed to demanding conditions during operation. The combination of thermal loads, plasma exposure as well as neutron induced damage and activation limits the number of materials suitable for this application. Due to its properties, tungsten (W) is foreseen as plasma-facing material (PFM) for the future DEMOnstration power plant. It is considered suitable due to its exceptionally high melting point, excellent thermal conductivity, low tritium retention and low erosion resistance during plasma exposure. But even tungsten armored PFCs have a limited lifetime due to, among other factors, surface erosion and the resulting thickness reduction of the armor material. In-situ local deposition of tungsten by means of additive manufacturing (AM) could counteract surface erosion and thus increase the service life span of PFCs. After evaluation of the potential AM processes qualified for this task, the wire-based laser metal deposition (LMD-w) process was selected as the most suitable process. First trials were conducted to examine if it is possible to reliably deposit tungsten onto tungsten substrate using the LMD-w process. In these first studies, single welding beads were generated, and in later experiments, entire layers were created from several welding beads which are arranged next to each other. To ensure reproducibility of the results, the substrate temperature was kept constant. Further experiments aimed at the elimination or minimization of problems such as oxidation, occurrence of balling defects, porosity, cracking, surface waviness and insufficient connection to the substrate. To increase the welding bead quality, the input parameters like laser power, deposition velocity, wire feed rate, inert gas flow, as well as the wire position were optimized. Furthermore, stacking of several layers, as well as the remelting of an already created layer, were carried out and investigated. This study represents the first steps in testing the feasibility of an in-situ surface regeneration concept for PFCs.
  • Publication
    Emissionsminderung beim Laserauftragschweißen
    ( 2022)
    Gräfe, Stefan
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    Paulus, Rebecca
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    Wohter, Daniel
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    Day, Robin
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    Bergs, Thomas
    Wire-based laser metal deposition (LMD-w) releases welding fume particles that are harmful to health and the environment. The potential hazard depends on the chemical composition as well as particle number and size. Using a statistical design of experiments, the emissions are characterized and the depen-dence on relevant process factors is determined. From this, process-intrinsic measures for emission reduction are derived.
  • Publication
    Express Wire Coil Cladding as an Advanced Technology to Accelerate Additive Manufacturing and Coating
    ( 2022)
    Gipperich, Marius
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    Riepe, Jan
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    Day, Robin
    ;
    Bergs, Thomas
    Metal shafts are indispensable components in mobility, energy and mechanical engineering. In such applications, the shafts need to withstand severe mechanical loads, friction, high temperature or corrosive media. This is why shafts are often completely made of high-performance alloys. From a technical point of view, coating an inexpensive base shaft with a thin layer of high-performance material is mostly sufficient to ensure its functionality. Adding functional parts such as bearing seats by Additive Manufacturing (AM) is an advantageous approach to increase flexibility and material efficiency. Reliable and economic AM processes need to be developed further, and laser-based processes such as wire-based Laser Metal Deposition (LMD-w) offer high potential to accomplish this. Due to their low deposition rate, however, LMD processes are not economically competitive with high-speed subtractive technologies. Motivated by this challenge, we present an alternative approach for laser-based shaft cladding. Instead of adding the filler wire continuously, wire coils are wound and preplaced on the shaft. In a second step, laser processing while rotating the part generates a metallurgical bond between the wire and the substrate. In this study, several solid and flux-cored wires were analyzed regarding their suitability for this two-step coil winding and LMD process. The resulting surface state and the welded joint quality are evaulated. Metallographic cross sections show low porosity and small heat-affected zones. Thanks to its good scalability, this innovative process can help strongly increase the build-up rate compared to classic LMD-w.
  • Publication
    Tailored melt pool shape by dual laser beam LMD-w process
    ( 2020)
    Gipperich, Marius
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    Riepe, Jan
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    Day, Robin
    ;
    Bergs, Thomas
    Additive Manufacturing (AM) is a fast growing manufacturing market. Laser Metal Deposition (LMD) is a high deposition rate metal AM process mostly used for repair, cladding or manufacturing applications. The two commonly used LMD-processes are powder-based (LMD-p) and wire-based (LMD-w). While LMD-p offers high deposition rates up to 2 kg/h (compared to LMD-w with 1kg/h) the handling of powder in terms of health and safety as well as machine wear become important. Furthermore, the material efficiency (due to overspray) is lower compared to the LMD-w AM-process. This is where LMD-w offers advantages, but advanced concepts to improve the stability of the LMD-w process to the level of LMD-p are needed. In this presentation, an approach is investigated to stabilize the LMD-w process by combining continuous wave (cw) laser and low-power pulsed wave (pw) laser. Calorimeter-like absorption measurements as well as deposition experiments are carried out to understand the physical background of the dual laser process and how this setup helps to stabilize the process. Promising results were achieved showing the possibility to tailor the melt pool height and width by a factor of 1.5-2 and an increase of energy absorption by 20%. This leads to a new perspective for the LMD-w manufacturing process (3D part build up, cladding and repair) in many industry sectors such as mobility, energy and engineering.
  • Publication
    Tailored melt pool shape and temperature distribution by a dual laser beam LMD-w process
    ( 2020)
    Gipperich, Marius
    ;
    Riepe, Jan
    ;
    Day, Robin
    ;
    Bergs, Thomas
    Laser Metal Deposition (LMD) is a high deposition rate metal AM process used for repair, cladding or manufacturing. While wire-based LMD (LMD-w) offers several advantages such as high material efficiency and a safe and simple handling of the wire feedstock, advanced concepts are needed to increase the LMD-w process stability. In this presentation, an approach is investigated to stabilize the LMD-w process by combining a continuous wave (cw) laser and a low-power pulsed wave (pw) laser. Calorimeter-like absorption measurements as well as deposition experiments are carried out to understand the physical background of the dual laser process and how this setup helps to stabilize the process. Promising results were achieved showing the possibility to tailor the melt pool height and width by a factor of 1.5-2 and an increase of energy absorption by 20 %. This offers new perspectives for the LMD-w manufacturing process in many industry sectors.