Magnetic pulse welding

Magnetic pulse welding (MPW) is a welding process that uses magnetic forces to drive two workpieces together and weld them together. The welding mechanism is most similar to that in explosion welding.^[1]

Process

A very high AC current (the "primary current") is passed through a conductive coil (the "inductor") near an electrically conductive material (the "flyer"). An intense magnetic field is locally produced that generates a secondary eddy current in the flyer according to Lenz's Law. The net effect of the secondary current moving in the primary magnetic field is the generation of a Lorentz force, which accelerates the flyer at a very high velocity. A stationary material (base material) is positioned in the trajectory of the flyer thus producing an impact which causes a solid state weld. Magnetic pulse welding may be used to join dissimilar metals.

Primary currents as high as 1 million amperes are used and flyer velocities in the vicinity of 800 meters per second can be achieved over a distance of a few millimeters. The magnetic pulse welding system is a high frequency capacitor discharge circuit (RLC circuit) often with extreme energy and power characteristics. System energies as high as 100 kJ, power of up to 1 GW and magnetic field intensities of 50 teslas and higher can be seen, which can propel certain materials at extreme velocities of 600 to 1000 m/s.

References

1. ^ Weman, Klas (2003), Welding processes handbook, CRC Press, pp. 91–92, ISBN 9780849317736, http://books.google.com/books?id=yIJm5uL9_sAC&pg=PA91. 

External links

• The Electromagnetic Pulse Technology (EMPT): Forming, Welding, Crimping and Cutting By R. Schäfer, P. A. Pasquale and S. W. Kallee
• Automotive Applications of Electromagnetic Pulse Technology (EMPT) By S. W. Kallee, R. Schäfer and P. A. Pasquale
• New materials, processes, and methods technology By Mel M. Schwartz