Magnetic Particle Inspection

Magnetic particle inspection is suitable for detecting discontinuities (e.g. cracks) in or near the surface of ferromagnetic mate-rials. The workpiece must be magnetized in the test area. The discontinuity can be shown best if the magnetic field is vertical to the discontinuity. One possible method for magnetization is using a yoke. The magnetic flux flows into the workpiece through a ferroma-gnetic yoke. The main field direction is the connection line between the two poles of the yoke. Yokes can be installed in a test bench so that the whole material can be magnetized. If hand yokes are used only the region between the two poles can be magne-tized. Multi-directional magnetization can be used to find discontinuities in any direction.