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Designing Magnets

Basic Design Consideration

A few basic and often simple alterations to a magnetic circuit could result in a dramatic improvement in the results achieved from magnets.

  • Magnetic flux lines always start at one pole and end at the opposite pole.
  • Magnetic flux lines take the path of least resistance.
  • Magnetic materials such as iron have a low resistance for magnetic fields.
  • The resistance to a magnetic field of air is about 1000 times higher than iron.
  • Air gaps in the path between the poles represent a high resistance to magnetic flux.
  • If the metal in a magnetic circuit is too thin it will saturate. Once metal saturates it is difficult to increase the flux in the circuit.
  • Flux lines will take the shortest air gap between poles.
Choice of magnet materials
Diagram indicates the size of magnet required to produce a flux density of 100mT at point P a distance of 5 mm from the pole face using various magnetic materials