Conference Agenda

Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).

Please note that all times are shown in the time zone of the conference. The current conference time is: 7th Dec 2021, 10:51:08am CET

Program for LiM 2021
Macro: Beam Oscillation
Thursday, 24/June/2021:
1:30pm - 2:30pm

Session Chair: Prof. Thomas Graf, University of Stuttgart, Germany
Location: Room 1
ICM Ground Floor 125

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1:30pm - 1:45pm

High speed videography of gap bridging with beam oscillation and wire feeding during the laser welding of stainless steel and aluminum alloys

Davide Maria Boldrin, Matteo Colopi, Simone D'Arcangelo, Leonardo Caprio, Ali Gökhan Demir, Barbara Previtali

Politecnico di Milano, Italy

Laser beam welding is known for its quality and speed. Given its susceptibility to gaps, the technology is applied in the industrial field with hard automation and dedicated fixtures rather than small-batch production. The latter cannot always guarantee the strict conditions on the fit-up of joints, especially with complex geometries. Gap-bridging techniques may be exploited to overcome these inaccuracies. The present work investigates the simultaneous use of low frequency circular beam oscillation and wire feeding as means to produce a continuous weld seam in the presence of constant air gaps. Lap joint welding of 2 mm-thick AISI301LN and butt joint welding of 3 mm-thick AW6005A-T6 alloy were conducted with gaps up to 1mm. High-speed imaging at 10kHz provided an insight in the dynamics of the oscillating weld pool and spatter formation. Optical inspection and metallographic analyses were used to verify the gap-bridging capability as well as the resulting seam quality.

1:45pm - 2:00pm

Influence of laser beam welding with overlaid high-frequency beam oscillation on weld seam quality and fatigue strength of aluminium wrought and die-cast joints

Benjamin Keßler, Dirk Dittrich, Robert Kühne, Markus Wagner, Axel Jahn

Fraunhofer Institute for Material and Beam Technology IWS, Dresden

Legal regulations with the aim of avoiding carbon dioxide emissions are drivers of innovation for lightweight automotive design.The economic production of such components is mainly achieved by using aluminium die-casts. A limiting factor for the use of aluminium die-castings is their weldability. The laser beam welding with overlaid high-frequency beam oscillation (LBW-HF) is a suitable solution to overcome this limitation.

In the proposed paper, weld specimens in form of aluminium mixed joints (wrought and die-cast alloys) were produced with the LBW-HF and with the static laser beam welding process (LBW). The weld seam quality is correlated with the tensile and fatigue strength properties. Furthermore, the results from the fatigue test are classified in the existing IIW regulations and their applicability with regard to laser-welded aluminium joints will be discussed. The results show an increased fatigue strength, especially for the LBW-HF process, compared to current used standards for design.

2:00pm - 2:15pm

Investigation of the influence of beam oscillation on the laser beam cutting process using high-speed X-ray imaging

Jannik Lind1,2, Jonas Wagner1, Niklas Weckenmann2, Weber Rudolf1, Thomas Graf1

1Institut für Strahlwerkzeuge (IFSW), University of Stuttgart, Germany; 2Precitec GmbH & Co. KG, Germany

Recently, it was shown that oscillating the laser beam during laser beam cutting can increase the maximum cutting feed rate compared to cutting with a static beam. In order to investigate this phenomenon, the geometry of the laser cutting front was observed by means of online high-speed X-ray imaging. Fusion cutting of 10 mm thick samples of stainless steel was recorded with a framerate of 1000 Hz. When the beam was oscillated in longitudinal direction, the maximum cutting feed rate could be increased by 25% compared to cutting with a static laser beam. In the talk, the influence of the oscillation parameters on the cutting speed, the cutting front geometry and the resulting cut quality will be discussed.

2:15pm - 2:30pm

CFD simulations for laser oscillation welding

Pareekshith Allu1, Frieder Semler2

1Flow Science Inc., United States of America; 2Flow Science Deutschland GmbH, Germany

Computational fluid dynamics (CFD) models have shown that laser keyhole welding at high speeds and powers can result in weld joints with reduced porosity. However, the process is limited by available laser powers (~6kW) and by insufficient penetration due to high welding velocities. To enable high speed welds with reduced porosity and optimal gap bridging, researchers have investigated laser oscillation welding. In this presentation, we look at some case studies where CFD models that simulate the laser-material interaction, melt pool dynamics and keyhole formation are developed to investigate laser oscillation welding in Zinc-coated steels. Additionally, these models helped identify zones of high Zinc vapor pressure that led to spatter and the data is compared to melt pool videos taken of the welding process. Such CFD models help develop welding schedules that limit the build of Zinc Vapor pressure in the melt pool and reduce spatter in laser oscillation welding.

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