Laser Tools in the Manufacturing Process

Graudenz, M.; Heitmanek, Marco

doi:10.1002/latj.201290049

Cited by 10 publications

(3 citation statements)

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“…In addition to achieving the strength requirements for car body parts, the process is distinguished by the high optical seam qualities that can be attained [2]. Therefore, it is used in car body construction to connect parts with customer-visible seams [3]. Standard application provides, for example, the connection between the two-part trunk lid [4] or the connection of roof and side panel [5].…”

Section: Introductionmentioning

confidence: 99%

Investigations on the occurrence of different wetting regimes in laser brazing of zinc-coated steel sheets

2020

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In the automotive industry, the seam edge quality of laser brazed seams is a crucial factor for the required high optical quality standards of customer-visible connections of zinc-coated car body parts. The type of zinc coating is decisive for the resulting geometry of the seam edges, which are aspired to be straight. Especially brazing of hot-dip galvanised steel with conventional brazing setup is not resulting in seam edges which fulfil the required optical quality. In this study, the wetting of copper-based filler wire on electrogalvanised and hot-dip galvanised steel sheets is analysed to increase the understanding of the influence of the wetting fronts on the seam edge quality. For this, the wetting fronts are determined in high-speed camera images and the resulting seam edges are captured by microscopic pictures. The results show that two major wetting regimes occur on both types of zinc coatings but with a different occurrence probability: one with a steep wetting front and zinc evaporation in front of wetting ("steep-angle-wetting") and one where liquid zinc connects with the wetting front and creates a flat wetting angle ("flat-anglewetting"). It is found that the resulting seam edge quality is mainly depending on the present wetting regime. However, for flatangle-wetting, in the regime with insufficient seam edge quality, a self-stabilising effect is identified, which is responsible for a missing process window for brazing of hot-dip galvanised steel with sufficient seam edge quality.

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Section: Introductionmentioning

confidence: 99%

Investigations on the occurrence of different wetting regimes in laser brazing of zinc-coated steel sheets

2020

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“…Standard applications are a connection between the two-part trunk lid [4] or the connection of the roof and side panel [5]. The brazed seams remain directly visible (except for painting) to the customers [6], and hence, the highest optical quality standards are demanded for these seams [7]. This includes, for example, straight seam edges, a smooth seam surface, and the absence of adherent spatter or pores and holes [8].…”

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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“…Consequently besides maximum output power, beam quality and stability over time are important properties of laser sources [2]. Until now mainly CO 2 , disk and fibre lasers are used [3]. Fig.…”

Section: Introductionmentioning

confidence: 99%

Qualification of Direct Diode Lasers for Laser Beam Welding in Order to Enhance Process Efficiency

Schaumberger

Mödl

Mann

et al. 2018

AMM

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Laser beam welding has become an established joining technique in automotive manufacturing. Common solid-state lasers generate high-quality joints, but they provide low energy efficiency. By contrast, direct diode lasers (DDL) have superior energy efficiency, are cheaper to purchase and additionally require less utility space. To examine the overall performance of direct diode lasers in comparison to disk lasers, welding quality and energy consumption of the two lasers have to be evaluated. Additionally, for this contribution the stability of the DDL’s beam, like temporal variation of focus position and beam shape, is examined. It is found that a focus shift takes place for longer periods of emission, but the variation of the focus diameter in the initial focal plane is negligible. As expected, the direct diode laser consumes less energy than the disk laser for the same output power. Welding experiments are conducted using four different steel alloys that are exemplary for engineering materials used in automotive manufacturing. Metallographic analysis shows that weld seam depths and widths are on average larger using the disk laser. However even with the need for higher output powers to achieve equal seam geometries the DDL consumes less energy and thereby causes less costs.

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Laser Tools in the Manufacturing Process

Cited by 10 publications

References 0 publications

Investigations on the occurrence of different wetting regimes in laser brazing of zinc-coated steel sheets

Investigations on the occurrence of different wetting regimes in laser brazing of zinc-coated steel sheets

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

Qualification of Direct Diode Lasers for Laser Beam Welding in Order to Enhance Process Efficiency

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