Means of creating a magnetic field
Magnetic particle testing - Practical aspects

Magnetic particle testing is based on a simple physical principle that relies on the behaviour of ferromagnetic materials subjected to an external magnetic field. However, a large part of the technical nature of the inspection depends on the match between the part to be inspected, the characteristics of the discontinuities sought and the means used to create this magnetic field. Numerous possibilities are available to the designers of checking fixtures, and the following paragraphs provide a representative list of the most common, though by no means exhaustive.