Electromagnetic forming

The magnetic pulse and the extreme deformation speed transforms the metal into a visco-plastic state – increasing formability without affecting the native strength of the material.

A rapidly changing magnetic field induces a circulating electric current within a nearby conductor through electromagnetic induction.

Because of Lenz's Law, the magnetic fields created within the conductor and work coil strongly repel each other.

A huge pulse of current is forced through the work coil by rapidly discharging a high-voltage capacitor bank using an ignitron or a spark gap as a switch.

The metal forming process occurs extremely quickly (typically tens of microseconds) and, because of the large forces, portions of the workpiece undergo high acceleration reaching velocities of up to 300 m/s.

A pinched aluminium can, produced from a pulsed magnetic field created by rapidly discharging 2 kilojoules from a high-voltage capacitor bank into a 3-turn coil of heavy gauge wire.
When the switch is closed, electrical energy stored in the capacitor bank (left) is discharged through the forming coil (orange) producing a rapidly changing magnetic field which induces a current to flow in the metallic workpiece (pink). The current flowing the workpiece produces a corresponding opposite magnetic field which rapidly repels the workpiece from the forming coil, reshaping the workpiece — in this case, compressing the diameter of the cylindrical tube. The reciprocal forces acting against the forming coil are resisted by the ' supportive coil casing (green).