In situ X-ray tomography investigations on laser welding of copper with 515 and 1030 nm laser beam sources

Hummel, Marc; Külkens, Mike; Schöler, Christoph; Schulz, Wolfgang; Gillner, Arnold

doi:10.1016/j.jmapro.2021.04.063

Cited by 24 publications

(10 citation statements)

References 8 publications

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“…This leads to the misleading expectation that both trends together will hold for shorter wavelengths, in turn leading to even higher absorptivity values for molten copper. Meanwhile, first simulative approaches seem to follow this expectation and assume increasing absorptivity values with temperature even in the green wavelength regime for their analyses [86].…”

Section: Process Stability Criterionmentioning

confidence: 97%

Why Color Matters—Proposing a Quantitative Stability Criterion for Laser Beam Processing of Metals Based on Their Fundamental Optical Properties

Kohl

Kaufmann

Schmidt

2022

Metals

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With its excellent automation capability and localized energy input enabling precise, reproducible welds, laser beam welding represents a preferred industrial joining technology. Electro-mobility drastically increases the need for defect-free and automatable copper joining technologies. However, copper welds that are produced with state-of-the-art infrared lasers often suffer from spattering and porosity. Recent publications show distinct improvements using novel beam sources at visible wavelengths, attributing them to increased absorptivity. Nevertheless, this cannot fully explain the steadier process behavior. This wavelength-dependent process stability has not yet been investigated sufficiently. Therefore, we have developed a predictive material-dependent criterion indicating process stability based on the example of copper heat-conduction spot welding. For this purpose, we combined energy balances with thermo-physical material properties, taking into account the wavelength and temperature dependence of the optical properties. This paper presents the key mechanism that we identified as decisive for process stability. The criterion revealed that X-points (unique, material-specific wavelengths) represent critical stability indicators. Our calculations agree very well with experimental results on copper, steel and aluminum using two different wavelengths and demonstrate the decisive, material-dependent wavelength impact on process stability. This knowledge will help guide manufacturers and users to choose and develop beam sources that are tailored to the material being processed.

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Section: Process Stability Criterionmentioning

confidence: 97%

Why Color Matters—Proposing a Quantitative Stability Criterion for Laser Beam Processing of Metals Based on Their Fundamental Optical Properties

Kohl

Kaufmann

Schmidt

2022

Metals

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“…The customized experimental setup for the investigation is based on the setup presented in Ref. [39], which was realized in cooperation with the RWTH Aachen University and the Fraunhofer Institute for Laser Technology (ILT). The installed setup at beamline P07-EH4 is shown in Figure 2.…”

Section: Laser Beam Welding Setupmentioning

confidence: 99%

“…A similar system using a microfocus tube as the X-ray source was previously used to study the welding process in ref. [39], and high-speed synchrotron X-ray imaging experiments were performed at the European Synchrotron Radiation Facility (ESRF) at Beamline ID19 using a multi-mode fiber laser on copper [17]. However, the herein presented in situ observations of the keyhole and melt pool geometry were achieved using high-speed X-ray imaging in side-and front-view at a frame rate of 1000 fps with a spatial resolution of 417 pixels/mm and a radiated area of approximately 2 mm in diameter.…”

Section: Laser Beam Welding Setupmentioning

confidence: 99%

Characterization of Vapor Capillary Geometry in Laser Beam Welding of Copper with 515 nm and 1030 nm Laser Beam Sources by Means of In Situ Synchrotron X-ray Imaging

Kaufmann

Forster

Hummel

et al. 2023

Metals

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Laser welding of copper is being used with increasing demand for contacting applications in electric components such as batteries, power electronics, and electric drives. With its local, non-contact energy input and high automation capability enabling reproducible weld quality, this joining technology represents a key enabler of future mobility systems. However, a major challenge in process design is the combination of energy efficiency and precise process guidance in terms of weld seam depth and defect prevention (i.e., spatter and melt ejections) due to the high electrical and thermal conductivity of copper. High-power lasers in the near infrared wavelength range (𝜆 ≈ 1 μm) and excellent beam quality provide an established joining solution for this purpose; nevertheless, the low absorptivity (≤5%) advocates novel beam sources at visible wavelengths due to altered absorptivity (40% at 515 nm) characteristics as an improved tool. In order to understand the influence of laser wavelength and process parameters on the vapor capillary geometry, in situ synchrotron investigations on Cu-ETP with 515 nm and 1030 nm laser sources with the same spot diameter are compared. The material phase contrast analysis was successfully used to distinguish keyhole and melt pool phase boundaries during the welding process. A significantly different sensitivity of the keyhole depth in relation to the feed rate was found, which is increased for the infrared laser. This behavior could be attributed to the increased effect of multiple reflections at 1030 nm.

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“…Marc Hummel and his team investigated laser welding of copper welded by 515nm and 1030nm laser beam sources. They selected suitable parameters to weld copper joints, which were independent of the wavelengths of laser beam sources [7].…”

Section: Literature Of Laser Beam Welding Technologymentioning

confidence: 99%

Experiment of lithium ion accumulator cells welding with diode laser

Kovács

Hareancz

2022

IOP Conf. Ser.: Mater. Sci. Eng.

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Accumulator cells have an important role in today’s industry. It produces a need to connect them, and there are several ways to make the bonds. We examined in this experiment already made resistance projection welded bonds, and we created laser beam welded bonds with various geometries. We tried to find out, which geometry produces the greatest bonds and which parameters will be the best solution.

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In situ X-ray tomography investigations on laser welding of copper with 515 and 1030 nm laser beam sources

Cited by 24 publications

References 8 publications

Why Color Matters—Proposing a Quantitative Stability Criterion for Laser Beam Processing of Metals Based on Their Fundamental Optical Properties

Why Color Matters—Proposing a Quantitative Stability Criterion for Laser Beam Processing of Metals Based on Their Fundamental Optical Properties

Characterization of Vapor Capillary Geometry in Laser Beam Welding of Copper with 515 nm and 1030 nm Laser Beam Sources by Means of In Situ Synchrotron X-ray Imaging

Experiment of lithium ion accumulator cells welding with diode laser

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