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Session Chair: Dr. Stefan Kaierle, Laser Zentrum Hannover e.V., Germany
Location:Room 2 ICM
11:15am - 11:30am
Development of SLM 3D printing system using galvano scanner for pure copper additive manufacturing by 200W blue diode laser
Keisuke Takenaka1, Yuji Sato1, Koji Tojo2, Masahiro Tsukamoto1
1Joining and Welding Research Institute, Osaka University, Japan; 2Shimadzu Corporation, Japan
Selective laser melting (SLM) is one of laser additive manufacturing technologies. Because absorptance of blue light on pure copper materials is higher than that of conventional near-infrared light, a blue diode laser is expected to effective in shaping pure copper parts. In our previous study, we developed a high power and high intensity blue diode laser with the wavelength of 450 nm. Output power and fiber core diameter was 200 W and 100 µm, respectively. In this study, we have developed a SLM machine using galvano laser scanner with the 200 W blue diode laser. The laser power and the scanning speed were changed to form a pure copper parts in the SLM method, and the influence of them on the cross-sectional area of the parts was investigated.
11:30am - 11:45am
3D printing of high-density copper parts using common NIR CW laser systems at moderate powers
Hagen Kohl1, Lisa Schade1, Gabor Matthäus1, Tobias Ullsperger1, Burak Yürekli1, Brian Seyfarth1,2, Bernd Braun3, Stefan Nolte1,2
1Institute of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, Germany; 2Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Center of Excellence in Photonics, Germany; 3Nuremberg Institute of Technology Georg Simon Ohm, Germany
Additive manufacturing (AM) of pure copper using laser assisted powder bed fusion (LPBF) at a wavelength of 1070 nm is demonstrated. In comparison to established LPBF materials, pure copper exhibits an extremely high reflectivity for wavelengths around 1 µm and the highest thermal conductivity among other AM materials. Although, pure copper is one of the most interesting materials for AM, the interplay of these characteristics still prevents copper to be applied using common laser-based AM machines. In this work, we demonstrate a wide processing window for 3D-printing of high-density copper parts based on a fiber laser as widely used in common AM machines. These achievements were obtained with the help of a self-developed numerical model that guided our experimental studies during the LPBF process. After process optimization, relative densities over 99 % can be demonstrated without the help of intense preheating or post processing like hot isostatic pressing.
11:45am - 12:00pm
Energy coupling in laser powder bed fusion of copper using different laser wavelengths
Klaus Behler2, Daniel Heussen1, Marvin Kupper1, Nobert Pirch1, Tim Lantzsch1, Johannes Henrich Schleifenbaum3
1Fraunhofer-Institut für Lasertechnik ILT, Aachen, Germany; 2Technische Hochschule Mittelhessen, Friedberg, Germany; 3RWTH Aachen University Lehrstuhl für Digital Additive Production DAP
Highly conductive pure copper is crucial for high current applications in electrical and mechanical engineering. The additive manufacturing of components from pure copper using laser powder bed fusion (LPBF) with conventional machine technology and "infrared" laser radiation (λ ≈ 1070 nm) is challenging due to the high reflectivity of copper for infrared laser light. Fraunhofer ILT has been investigating possibilities to use lasers within the visible spectral range (green @ λ=515 nm and blue @ λ=450 nm) in the LPBF process. It has been shown that there is a potential to improve energy coupling and process stability applying such lasers in the LPBF process. In this paper calorimetric absorptivity measurements are presented, showing the influence of wavelength and process parameters as well as material conditions on the effective energy input for the melting of copper substrate material as well as of powder material.
12:00pm - 12:15pm
Laser powder bed fusion (L-PBF) of pure copper using a 1000 W green laser TruDisk
Additive manufacturing of pure copper with lasers is complex using usual near IR laser wavelength, due to a high reflectance (~95 % at 1.07µm) combined with a high conductivity. This results in limited parts density, never exceeding 99%, whereas other metals can easily reach 99.9 % density. A possible way of improvement is to reduce the laser wavelength (from near IR to green) to enhance laser absorption and reduce the power needed to provide deep and stable tracks. In the current work, a detailed study was carried out with the use of a 1 kW cw green laser implemented on a L-PBF prototype. Two objectives were considered: (1) investigating the laser absorbance during single L-PBF tracks at various energy densities and welding regimes (conduction, keyhole) and (2) building various 3D parts and optimizing their density. Finally, parametric study allowed obtaining up to 99.9 % dense parts from pure copper powder.
12:15pm - 12:30pm
Additive manufacturing of conductive copper traces on 3D geometries by laser-sintering
Ejvind Olsen, Ludger Overmeyer
Leibniz Universität Hannover, Germany
These days, additive manufacturing processes cover an extensive range of materials. A new trend is a growing interest in the implementation of additional functions like electrical circuits. Combining full-surface primer and copper ink coating from printed electronics with laser processing enables integrating conductive traces directly on the surface of 3D-printed components. Priming reduces the roughness of the 3D printed (multi-jet modeling) circuit carrier below 100 nm. Afterward, the metal-containing ink is dip-coated, dried, and sintered locally by laser processing. The used laser system includes a focused and pulsed 1064 nm laser beam controlled by a scanner with three optical axes (x, y and z-direction). This research presents a detailed investigation on the influence of 3D geometrical factors like radii and sidewall angle on the resulting conductive trace resistance. Electron beam imaging technology with energy dispersive x-ray spectroscopy characterizes the conductive tracks regarding geometric and material properties.