Abstract
Magnetic particle inspection is one of the most commonly used non destructive testing methods for detecting surface and limited subsurface indications in ferromagnetic materials. The magnetic field provides the means by which indications are formed and detected. It is thus essential that the magnetic field be optimized, not only in magnitude, but also in direction when detection of specific indications is required. For example, too low a field strength would not result in adequate particle build-up and would thus reduce the probability of detection for small indications.