Thomas Seefeld
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View article: Laser melt injection of niobium carbide on aluminium bronze substrates for enhanced cavitation erosion resistance
Laser melt injection of niobium carbide on aluminium bronze substrates for enhanced cavitation erosion resistance Open
Cavitation erosion (CE) is detrimental to a number of engineering components, including ship propellers and pump impellers. Due to deformation and mass loss, CE significantly impairs the serviceability of these components and results in tr…
View article: Influence of intensity distributions on the process dynamics during laser deep penetration welding of pure nickel with a flexible ring mode laser source
Influence of intensity distributions on the process dynamics during laser deep penetration welding of pure nickel with a flexible ring mode laser source Open
Current research results demonstrate the potential of spatter reduction in laser deep penetration welding by using adapted laser beam intensity distributions between a ring and a core intensity. The spatter-reducing effect, resulting from …
View article: Influencing the powder particle transport in high-speed laser melt injection
Influencing the powder particle transport in high-speed laser melt injection Open
Using high-speed laser melt injection (HSLMI), it is possible to generate wear-resistant metal matrix composite (MMC) surfaces on tools with great productivity. Since high laser intensities are required for reaching high process speeds, st…
View article: Influence of the inner roughness of powder channels on the powder propagation behavior in laser metal deposition
Influence of the inner roughness of powder channels on the powder propagation behavior in laser metal deposition Open
The powder propagation behavior of powder nozzles for the laser metal deposition process has a significant influence on powder utilization rate and track geometry. A well-focused powder stream will lead to a higher process efficiency and l…
View article: Laser metal deposition of Al 7075: Effects of TiC nanoparticles
Laser metal deposition of Al 7075: Effects of TiC nanoparticles Open
High-density defects in additively manufactured components cause poor mechanical properties and premature failure. The present paper aims in minimizing defects in laser metal deposition (LMD) of high-strength aluminium alloy 7075. The effe…
View article: Identifying the direction of weld path deviations in laser deep penetration welding of hidden T-joints by means of OCT
Identifying the direction of weld path deviations in laser deep penetration welding of hidden T-joints by means of OCT Open
In laser beam welding of hidden T-joints, the web sheet is completely covered by the face sheet, thus impeding the determination of the relative position between the laser beam and the web sheet. This circumstance usually raises high deman…
View article: Influence of Alloy and Solidification Parameters on Grain Refinement in Aluminum Weld Metal due to Inoculation
Influence of Alloy and Solidification Parameters on Grain Refinement in Aluminum Weld Metal due to Inoculation Open
The goals are: (1) Establish how much Ti/B grain refiner is need to completely refine aluminum weld metal for different alloys and different welding conditions; (2) Characterize how alloy composition and solidification parameters affect we…
View article: Adaptive powder nozzle setup for enhanced efficiency in laser metal deposition
Adaptive powder nozzle setup for enhanced efficiency in laser metal deposition Open
Laser metal deposition (LMD) is a blown powder process used for the additive manufacturing of large and/or complex parts. The laser spot size is determined by the fiber optic cable and the imaging ratio of the process optics. Spot sizes ty…
View article: Texturing skin-pass rolls by high-speed laser melt injection, laser ablation, and electrolytic etching
Texturing skin-pass rolls by high-speed laser melt injection, laser ablation, and electrolytic etching Open
Skin-pass rolls are used for setting the final sheet thickness and surface texture. For sheet metal that is produced for forming, textured skin-pass rolls featuring a high-low structure are used in order to improve the formability and pain…
View article: In-process monitoring of track geometry as a control approach for laser metal deposition
In-process monitoring of track geometry as a control approach for laser metal deposition Open
Laser metal deposition (LMD) is an additive manufacturing process, which is used to generate large parts or for reconditioning machine components. During the process the welding tracks are affected by complex dynamic temperature-time curve…
View article: Temperature and distortion in laser melt injection of MMC wear-resistant coatings in a copper beryllium alloy
Temperature and distortion in laser melt injection of MMC wear-resistant coatings in a copper beryllium alloy Open
Wear-resistant coatings made of MMC materials (metal matrix composites) are ideal for increasing the service life of tools subjected to high abrasive stresses. Such MMC surfaces can be produced by laser melt injection during the manufactur…
View article: Characterization of optical emissions during laser metal deposition for the implementation of an in-process powder stream monitoring
Characterization of optical emissions during laser metal deposition for the implementation of an in-process powder stream monitoring Open
In laser metal deposition (LMD), the powder is fed into the laser-induced melt pool using different powder nozzles for the purpose of additive manufacturing and the generation of wear and corrosion protection coatings. So far, there are no…
View article: Interaction between Local Shielding Gas Supply and Laser Spot Size on Spatter Formation in Laser Beam Welding of AISI 304
Interaction between Local Shielding Gas Supply and Laser Spot Size on Spatter Formation in Laser Beam Welding of AISI 304 Open
Background. Spatter formation at melt pool swellings at the keyhole rear wall is a major issue for laser deep penetration welding at speeds beyond 8 m/min. A gas nozzle directed towards the keyhole, that supplies shielding gas locally, is …
View article: Automated Determination of Grain Features for Wire Arc Additive Manufacturing
Automated Determination of Grain Features for Wire Arc Additive Manufacturing Open
The morphology and size of the grains of the additively manufactured (AM) parts affect the mechanical properties and performance. The present research aimed to analyze the microstructure of AM parts, particularly the grain features, using …
View article: Influence of the process speed in laser melt injection for reinforcing skin-pass rolls
Influence of the process speed in laser melt injection for reinforcing skin-pass rolls Open
Laser melt injection is a technology for producing metal matrix composite (MMC) layers on tools such as skin-pass rolls by injecting hard particles into a laser-induced weld pool. However, low process speeds prevent the application of lase…
View article: Influence of oxygen content in the shielding gas chamber on mechanical properties and macroscopic structure of Ti-6Al-4V during wire arc additive manufacturing
Influence of oxygen content in the shielding gas chamber on mechanical properties and macroscopic structure of Ti-6Al-4V during wire arc additive manufacturing Open
Wire arc additive manufacturing (WAAM) of titanium parts shows promising potential for aerospace application due to its high deposition rates allowing a fast and economical production of large components. The cost savings are high, especia…
View article: Characterization of the powder stream propagation behavior of a discrete coaxial nozzle for laser metal deposition
Characterization of the powder stream propagation behavior of a discrete coaxial nozzle for laser metal deposition Open
Laser metal deposition (LMD) is a blown powder process which can be used for the additive manufacturing of large components or the generation of functional geometries on semifinished parts. In LMD, it is crucial that both the laser intensi…
View article: Improving the wear resistance of copper tools for pressure die casting by laser melt injection
Improving the wear resistance of copper tools for pressure die casting by laser melt injection Open
Highly conductive copper alloys are used for various tools in casting and welding technology. In pressure die casting, copper alloys are used for pistons pressing the metal melt into a die. The high thermal conductivity of these alloys all…
View article: Laser melt injection of spherical fused tungsten carbide in Cu-ETP with 515 nm wavelength laser
Laser melt injection of spherical fused tungsten carbide in Cu-ETP with 515 nm wavelength laser Open
Laser melt injection (LMI) is used to improve the wear resistance of highly loaded metal surfaces such as copper-based alloys for injection molds or casting tools. Therefore, a metal matrix composite (MMC) is formed by the injection of har…
View article: Advanced Process Monitoring in Additive Manufacturing
Advanced Process Monitoring in Additive Manufacturing Open
Laser‐based additive manufacturing processes like laser metal deposition (LMD) and laser powder bed fusion (LPBF) are becoming more and more popular in industry. In demanding applications, however, every part has to be tested non‐destructi…
View article: Measuring the melt pool size in a wire arc additive manufacturing process using a high dynamic range two-colored pyrometric camera
Measuring the melt pool size in a wire arc additive manufacturing process using a high dynamic range two-colored pyrometric camera Open
Control of the melt pool size is necessary to achieve more homogenous material properties in wire arc additive manufacturing (WAAM). The melt pool size can be measured by camera imaging or temperature field measurement. The paper aims to i…
View article: A multi-parameter control of track geometry and melt pool size for laser metal deposition
A multi-parameter control of track geometry and melt pool size for laser metal deposition Open
The present work demonstrates a multi-parameter control for constant track geometry and consistent layer height in laser metal deposition process. A two-channel pyrometric camera is used to maintain a constant melt pool size by a laser pow…
View article: Temperature field based closed-loop control of laser hot wire cladding for low dilution
Temperature field based closed-loop control of laser hot wire cladding for low dilution Open
A modified laser hot wire cladding process is demonstrated with beam oscillation for high productivity and low dilution. A 2-channel pyrometer camera is used to observe the melt pool geometry during process to evaluate the current status o…
View article: Reducing adhesive wear in dry deep drawing of high-alloy steels by using MMC tool
Reducing adhesive wear in dry deep drawing of high-alloy steels by using MMC tool Open
Sheet metal forming normally requires the application of lubricants to protect the tool and the sheet against wear. In the case of nonlubricated sheet metal forming, cleaning processes would not be necessary anymore and the process chain c…