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04.08.14 | Article of Salzgitter Mannesmann Forschung

YAG laser test facility

"YLVA" welds thick plate

SZMF's new YAG laser testing plant is setting new benchmarks in joining technology. Similar to other new major facilities of Salzgitter Mannesmann Forschung, the central test facility goes by the family name of "YLVA", a German abbreviation that stands for YAG laser testing plant. The new facility confers technical superiority in joining technology compared with the Salzgitter Group's laser welding equipment. And this is important - as research always needs to be at least one step ahead.

The facility uses a disk laser with an output of 16 kW. It is one of the few facilities in this performance class employed exclusively for research purposes in industrial enterprises, and it can safely weld plate and pipe material of up to 16 mm thick in one layer. The advantages of harnessing laser beams in welding lie in the comparatively low heat input from a concentrated supply of energy in conjunction with high processing speeds. In comparison with conventional welding processes, the system raises productivity and, depending on the individual application, also enhances the seam qualities.

In order to improve the gap bridging capability of the laser process, an additional feature that combines arc welding technology and oscillating the laser beam perpendicular to the weld seam has been installed. In addition, process-integrated inductive heat treatment can selectively influence the weld structure.

"YLVA" team: (from left) Dietmar Lotz, Dr. Matthias Höfemann and Prof. Wilko Flügge (SZMF, Salzgitter),
2nd from right, Dr. Wolfgang Scheller (SZMF, Duisburg)

Handling the equipment is facilitated by a 3D linear gantry system that, along with linear joining, also permits applications in the form of contour paths. Motion in the x direction is enabled by a positioning unit that is also capable of moving pipe segments up to 500 kg. By means of additional movements in y and z directions, in conjunction with a machine frame as a portal solution, complex components such as automotive components can be tested on the one hand, and sophisticated clamping technologies on the other, an example being cutting-edge tube clamping techniques for thin-walled sample tubes. The gantry system is generally designed to accommodate the sophisticated demands placed on positioning and repeat accuracy and accelerations of the laser machining process.

"YLVA" process layout

LabVIEW control, a flexible, programmable logic controller, is used to control the welding machinery and for contour and positioning control, as well as for the purpose of safety engineering and other peripherals. An IT-supported open control that can include other welding technologies, as well as handling and monitoring systems for integration into the test technology has been successfully implemented here.

This feature opens up new and interesting possibilities particularly – but not exclusively – for production processes in the manufacturing and processing of pipes in various dimensions, which applies to welded large-diameter and medium-format types as well as precision tubes, too. For instance, in the construction of jacket structures for wind turbines combining laser welding with arc welding is currently under discussion for joining pipe junctions.

Teaming up, the departments in Salzgitter and Duisburg specialized in joining technology create further customer benefits from their laser know-how, as well as their pipe and application expertise.

This cutting-edge joining technology can provide Salzgitter Flachstahl with even better support in promoting the development of grades and surface engineering - now and in the future, examples being thin automotive grades and thicker hot strip qualities for application in energy and transportation.

Furthermore, "YLVA" is important in two other areas: On the one hand, the test facility plays an important role in the process of approving materials for the automotive industry, for instance in testing the strength of laser welded joints of new steel grades. On the other, the internal Group's customers benefit from the option of obtaining key data for their laser processes, in addition to having their employees trained at SZMF. 

Monitoring and single pass-welding in cross section; 12 mm thick plate