Category Archives: Laser Welding

Electromagnetic Control of the Weld Pool Dynamics in Partial Penetration Laser Beam Welding of Aluminium Alloys

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By Vjaceslav Avilov, André Schneider, Marco Lammers, Andrey Gumenyuk, Michael Rethmeier

A well-known problem of partial penetration laser beam welding is keyhole-tip instability representing the main source of porosity – gas bubbles leave the keyhole near its tip. The second important problem of keyhole mode laser welding is very intensive thermocapillary (Marangoni) convection in the upper part of the weld pool. The surface tension cannot completely suppress oscillations of the weld pool surface and the re-solidified weld surface becomes very rough.

In the present work an oscillating (AC) magnetic field was used to suppress porosity formation and to stabilize the weld pool surface in bead-on-plate partial penetration up to 4.4 kW Nd:YAG laser beam welding of  AW-5754  plates in PA position. Two magnet poles (cross-section 25 x 25 mm2) were located left and right aside the weld pool. The magnetic field (up to 0.4 T(rms) and 10 kHz) was oriented perpendicularly to the welding direction. The AC power supply does not exceed 2 kW. The AC magnet weighs only 5 kg and allows easy assembly on the laser welding head. Continue reading →

Novel Fusion Welding Technology of Si/Glass Using Ultrashort Laser Pulses with High Pulse Repetition Rates

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By I. Miyamoto, Y. Okamoto, A. Hansen, T. Amberla, J. Vihinen, J. Kangastupa

Silicon/glass is one of the most widely used material combinations for sensing and actuating microsystems and micro electronic technologies. Anodic bonding has been most widely used for Si/glass bonding since its invention in 1969, because of its excellent mechanical properties and process throughput. There are, however, some disadvantages in anodic bonding that no space selectivity is available, and high temperature heating is needed for long time with applying high electric field. While several laser-based joining techniques including eutectic bonding, SLB (selective laser bonding) and fusion welding using ns laser pulses have been developed by several groups for utilizing their excellent space selectivity, the joint strength and process throughput are far behind the anodic bonding technique. Continue reading →

The Difference Between Fiber Lasers and Fiber Delivered Lasers

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By Tony Hoult 

Nobody would disagree that real change is occurring in the laser industry. In the broadest context, what is happening is a shift from the conventional technique of assembling lasers using free space optical components to a technique based on splicing together fiber based components.  It is now very widely accepted that this brings a range of benefits, not least of which are dramatic improvements in reliability, stability and ease of use. This shift can be seen across the whole spectrum of the laser industry from multi-kilowatt lasers to low power ultra-short pulse length lasers where more and more lasers use the key word ‘fiber’ in their descriptions. Continue reading →

Laser Welding: The Spatter Map

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Alexander F. H. Kaplan and John Powell

Luleå University of Technology, Dept. Applied Physics and Mechanical Engineering, Sweden

Welding defects have to be suppressed to maintain the mechanical strength of a product under load. For suitable choice of the process parameters operating windows can be entered where a certain welding defect can be suppressed. However, the identification of such operating windows is empirical and moreover difficult to transfer, as the process depends on 20-30 parameters and each industrial application used to be a different, thus new situation. Continue reading →

Welding Zinc Coated Steels: New Joint Design and Strategy with Scanner Technology

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By: Klaus Loeffler, Dr. Tim Hesse, Peter Kaupp

TRUMPF Laser und Systemtechnik GmbH, Ditzingen, Germany
TRUMPF Werkzeugmaschinen GmbH, Ditzingen, Germany

The existing problems of weld defects in welding zinc coated steels in a overlap situation are present in the automotive industry. Overlap joints are the most common type of joint geometry used in the automotive industry. In this case there are 2 layer of zinc coatings in between the two steel sheets. The boiling point of Zinc is at 906C and the melting point of steel at 1536C. The different boiling and melting points causes Zn outgassing. Welding with a technically zero gap creates weld defects by material ejection. The consequences are reduced strength of the weld, requirement of additional sealer and additional maintenance of the equipment. The technical work around are designed gaps between the sheet to allow controlled outgassing Extensive research has been taken on with highspeed cameras to evaluate the root cause. Continue reading →