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Anna Kochan: Anna Kochan is European Associate Editor for Assembly Automation.
New developments in magnetic pulse welding are opening up new applications for the technology. The developments are being led by two companies, working independently. One is Pulsar, a small Israeli company which is part of the massive Clal Industries group, and which reports major interest in the technology from General Motors. The other is Dana, a large US group, whose work on magnetic pulse welding won it the 1999 Automotive Manufacturing Award, presented by FT Automotive World.
The theory of pulse welding is based on the principal of magnetism that like poles repel each other. In the case of two tubes having to be welded together, for example, the ends of the two tubes would be placed slightly overlapping, one inside the other, but not touching. To create the weld, an electromagnetic coil would be placed around the outer one and magnetic fields created such that the pole of the coil is the same as the pole of the outer tube. By using an ultra-short pulse of very high electrical energy to power the coil, the force of repulsion between the coil and the outer tube is so great that the outer tube is driven away from the coil towards the stationary inner tube with such a high kinetic energy that, when the two hit, sufficient pressure is generated to create a weld (Figures 1 and 2).
Magnetic pulse welding has, in fact, been available for more than 60 years, but its use has been very limited up till now. Whereas previously, the process could only weld small diameter (less than 25mm) parts made of soft alloy materials, it...