The mutual repulsion causes pressure impulse on the work, which causes the metal to be rapidly accelerated and gain high kinetic energy. The kinetic energy forms the work piece by working the metal beyond its yield strength and causes permanent deformation. The forming pulses are kept short to reduce the loss of energy to resistance heat. The pulse length is between 10 and 100 micro seconds. The field shapers are used to concentrate the magnetic fields to where the forming is desired.
Field shapers a current-carrying conductors that are coupled to the forming coil.
The forming methods that EMF can be used for are compression, expansion, and contour forming. The process is very repeatable since the energy output is very adjustable, the only forming variable is the material. The process also requires no lubricant since the tool and the work piece never touch. The exception is when the work piece is driven against a mandrel, although the work piece still never touches the tool lubricant might be needed to get it out. There is also no spring back in the material when EMF is used.