HEAVY DUTY APPLICATIONS
supports or copper rails are used. These require mechanical attachment, detachment and possibly reworking of the root area, which costs additional time and money. An alternative patented solution, from WeldNova, is the use of oscillating electromagnetic fields to prevent root drops. This solution
is based on the generation of Lorentz forces in the weld pool. An oscillating magnetic field perpendicular to the welding direction is
removal is not necessary
• sheets with a wall thickness of up to 30 mm can be joined in a single layer with a laser power of only 20 kW, drop formation is avoided
• time-consuming seam preparation can be dispensed with, a plasma or flame cut is sufficient
• gaps and edge offsets of up to 2 mm can be safely bridged
• more homogeneous distribution of the filler metal over the entire weld depth can be achieved
was the possibility to expand the process parameter window to maintain desired cooling times and mechanical properties, without suffering adverse effects concerning the root quality of the weld. In addition to the economic advantages,
the laser hybrid welding process is also the ecologically cleaner alternative compared to SAW. The use of the process in industry is limited by process-specific challenges. The patented non-contact electromagnetic bath created with the WeldNova system expands the potential of laser hybrid welding in the thick plate range beyond 15 mm thick. The advantages of the electromagnetic bath support includes:
• works contactless, so mechanical attachment and
• process parameters can be extended to meet desired cooling times; positive influence on mechanical properties, especially notched impact strength.
The WeldNova magnet as a bath Thick-walled components can be welded
at lower welding speeds in horizontal or vertical positions with weld pool supports or using multilayer techniques. The size and weight of the components makes handling more difficult. Therefore, the use of a weld pool support is usually unavoidable. Conventional mechanical weld pool supports such as ceramic bath
www.welding-world.com WeldingWorld1 / 35
generated by an AC magnet and produces eddy currents in the material. The electric current density is parallel to the welding direction. The resulting Lorentz force is
directed upwards and counteracts the hydrostatic pressure. The non-contact electromagnetic weld pool support has already been successfully used in single- layer laser hybrid welding of S355J2 sheets up to 30 mm thick. This was carried out using a 20 kW laser system. Sheets up to a thickness of 25 mm can be welded with a square groove butt-joint. For higher plate thicknesses, a single V seam preparation with a total seam opening angle of about 30° - 45° and a root face of about 22 mm - 25 mm is preferred.
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