Advances in macro-scale laser processing

Schmidt, Michael; Zäh, Michael F.; Li, Lin; Duflou, Joost R.; Overmeyer, Ludger; Vollertsen, Frank

doi:10.1016/j.cirp.2018.05.006

Cited by 25 publications

(13 citation statements)

References 198 publications

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“…Given that the laser system efficiency is a fixed ratio, a reduction in direct energy would yield a proportional reduction in indirect energy, regardless of the specific laser system in use. In a similar way to that noted by Schmidt et al [21] for individual sub-components, there is cross-talk between different energy categories within the same sub-component as well;…”

Section: Discussionsupporting

confidence: 65%

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Characterisation of Laser System Power Draws in Materials Processing

Goffin

Jones

Tyrer

et al. 2020

JMMP

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Due to their high speed and versatility, laser processing systems are now commonplace in many industrial production lines. However, as the need to reduce the environmental impact from the manufacturing industry becomes more urgent, there is the opportunity to evaluate laser processing systems to identify opportunities to improve energy efficiencies and thus reduce their carbon footprint. While other researchers have studied laser processing, the majority of previous work on laser systems has focused on the beam–material interaction, overlooking the whole system viewpoint and the significance of support equipment. In this work, a methodical approach is taken to design a set of energy modelling terminologies and develop a structured power metering system for laser systems. A 300 W fibre laser welding system is used to demonstrate the application of the power characterization system by utilizing a purpose-built power meter. The laser is broken down according to sub-system, with each part analysed separately to give a complete overall power analysis, including all auxiliary units. The results show that the greatest opportunities for efficiency improvements lie in the auxiliary units that support the laser devices as these were responsible for a majority of the electrical draw; 63.1% when the laser was operated at 240 W, and increasing as the beam power reduced. The remaining power draw was largely apportioned to electrical supply inefficiencies. In this work, the laser device delivered a maximum of 6% of the total system power. The implications of these results on laser processing system design are then discussed as is the suitability of the characterization process for use by industry on a range of specific laser processing systems.

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Section: Discussionsupporting

confidence: 65%

“…It has also been identified that these variables are not independent between the various sub-systems. Schmidt et al [21] noted that laser selection would impact the relative size effect of power and cooling sub-systems.…”

Section: Energy Modelling In Laser Systemsmentioning

confidence: 99%

Characterisation of Laser System Power Draws in Materials Processing

Goffin

Jones

Tyrer

et al. 2020

JMMP

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“…Laser beam welding of metals is a widely used process in various industry sectors, e.g., the automotive industry [1,2]. Since the development of the first high-power beam sources, its applicability has steadily broadened and further expanded through the development of novel beam sources.…”

Section: Introductionmentioning

confidence: 99%

“…Since the development of the first high-power beam sources, its applicability has steadily broadened and further expanded through the development of novel beam sources. The change from the pioneering CO 2 lasers (λ = 10.6 µm) to solid-state lasers (λ ≈ 1 µm) realized as thin-disk or fiber lasers based on Yb:YAG and Nd:YAG led to strong increases in efficiency, absorptivity and applicability [2,3]. Due to the rapidly expanding market for electric mobility, copper, with its excellent electrical conductivity, and thus also copper joining-ranging from small applications, such as hairpins up to large cross-section applications like high-current conductors-has been gaining importance [4,5].…”

Section: Introductionmentioning

confidence: 99%

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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“…Laser material processing is a technology that is used for many applications in the production process of the automotive industry [1]. Here, laser brazing is used for the joining of car body parts [2], which are by default zinc-coated for corrosion protection [3].…”

Section: Introductionmentioning

confidence: 99%

The influence of the ratio between the wire and process velocities on the wetting process during laser brazing

Mattulat

Woizeschke

2020

Prod. Eng. Res. Devel.

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Laser brazing is used in automotive production for the joining of car body parts with customer-visible seams, whereby the highest optical seam quality is demanded. During the wetting process, a constriction formation can occur within the molten brazing material, which subsequently collapses; this induces a stepwise progression of the wetting front, thereby decreasing the optical seam quality. The aim of this study is to investigate the influence of the wire and process velocities on this constriction formation. For this purpose, high-speed recordings of the process zone are performed during laser brazing and then evaluated concerning the wetting process. The results show that the constriction formation depends on the relationship between the process velocity and the process direction component of the wire velocity. The constriction formation only occurs when the process velocity exceeds the parallel-oriented component of the wire velocity. This constriction formation is unstable and collapses repeatedly. In this study, increasing velocity differences stabilizes the constriction existence. This stabilization correlates with a uniform wetting process and a reduced frequency of the occurrence of blowout events, probably due to improved outgassing of zinc bubbles from the melt pool.

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Advances in macro-scale laser processing

Cited by 25 publications

References 198 publications

Characterisation of Laser System Power Draws in Materials Processing

Characterisation of Laser System Power Draws in Materials Processing

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

The influence of the ratio between the wire and process velocities on the wetting process during laser brazing

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