Swinging Field Technique/ Multidirectional Magnetisation

The swinging field technique is used to apply two mutually perpendicular fields in one operation. Whilst the technique appears to test in all directions simultaneously, it is not possible to align magnetic domains in multiple directions at the same time. Instead the two fields are applied in sequence, rapidly changing in direction.

An advantage of this technique is reduced inspection time. However, the efficiency of the swinging field technique is widely debated, with some standards forbidding its use, primarily due to problems arising with high retentivity materials whereby the domains become aligned in one direction and are unable to ‘swing’ to the next direction.

The swinging field technique is also restricted to the continuous magnetisation technique.