Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

48.5 MAGNETIC PULSE FORMING

 

· Basic operation,

  1. 1. A large current discharge is directed through a coil. The coil has been placed inside another shape.
  2. 2. The discharging current creates a magnetic field. In the nearby sheet of metal an opposing magnetic field is induced. The result is that the two magnetic fields oppose and a force moves the sheet away from the coil.
  3. 3. Over a period of time the part is deformed, often to the shape of a mandrel, or other form.

 

· Applications,

  1. - fittings for ends of tubes
  2. - embossing
  3. - forming

 

· Capacitor banks are used to accumulate charge for larger discharges.

 

· The part is formed to a mandrel that has a negative image of the part.

 

· The method generates pressures up to 50 Kpsi creating velocities up to 900 fps, production rates can climb to 3 parts a second.

 

· Applications,

  1. - ball joint seals
  2. - fuel pumps
  3. - baseball bats

 

· Generally there are three methods of magnetic forming,

  1. - swaging
  2. - expanding
  3. - embossing and blanking

 

· Swaging - An external coil forces a metal tube down onto a base shape (tubular coil).

 

· Expanding - an inner tube is expanded outwards to take the shape of an outer collar (tubular coil).

 

· Embossing and Blanking - A part is forced into a mold or over another part (a flat coil) - This could be used to apply thin metal sheets to plastic parts.

 

 

· Advantages,

  1. - easy to control
  2. - allows forming of metals to any material
  3. - no contact eliminates many requirements such as lubricants, heat dissipation, surface repair, etc.
  4. - parts are uniform
  5. - no tool wear
  6. - minimal operator skill
  7. - very strong joints
  8. - energy efficient
  9. - easy installation
  10. - high production rates (typically a few seconds)

 

· Disadvantages,

  1. - complex shapes not possible
  2. - no pressure variations over work
  3. - limits forming pressures