Possibilities for online process monitoring at laser brazing based on two dimensional detector systems

Grimm, Alexander; Schmidt, Michael

doi:10.2351/1.5061607

Cited by 12 publications

(5 citation statements)

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“…Industrial inline quality control systems are highly desired to answer laser-brazed welding quality requirements and overcome offline inspection efficiency limitations [8][9][10][11][12][13]. For this purpose, several commercially available NDT inspection technologies may be considered.…”

Section: Non-destructive Testing For Laser-brazed Weldingmentioning

confidence: 99%

New directions for inline inspection of automobile laser welds using non-destructive testing

Machado

Rosado

Mendes

et al. 2021

Int J Adv Manuf Technol

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An innovative pilot installation and eddy current testing (ECT) inspection system for laser-brazed joints is presented. The proposed system detects both surface and sub-surface welding defects operating autonomously and integrated with a robotized arm. Customized eddy current probes were designed and experimentally validated detecting pore defects with 0.13 mm diameter and sub-surface defects buried 1 mm deep. The integration of the system and the manufacturing process towards an Industry 4.0 quality control paradigm is also discussed.

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Section: Non-destructive Testing For Laser-brazed Weldingmentioning

confidence: 99%

New directions for inline inspection of automobile laser welds using non-destructive testing

Machado

Rosado

Mendes

et al. 2021

Int J Adv Manuf Technol

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“…Further analyses of the wetting behaviour were carried out by Grimm and Schmidt. High-speed camera recording of the process from the top view was done [17]. It is shown that for hot-dip galvanised steel, a cyclic wetting process takes place.…”

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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“…Grimm and Schmidt first reported these constrictions for a sound brazing process with constant process parameters, occurring at a frequency of approx. 30 Hz and inducing a stepwise progression of the wetting process [11]. They assume that the formation of constrictions depends on effects that are connected to the process velocity.…”

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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Possibilities for online process monitoring at laser brazing based on two dimensional detector systems

Cited by 12 publications

References 0 publications

New directions for inline inspection of automobile laser welds using non-destructive testing

New directions for inline inspection of automobile laser welds using non-destructive testing

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

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