MAGNETIC PARTICLE TESTING
Magnetic Particle Testing (MPT), also referred to as Magnetic Particle Inspection, is a non-destructive technique used to detect surface and slightly subsurface flaws in most ferromagnetic materials such as iron, nickel, and cobalt, and some of their alloys. Because it does not necessitate the degree of surface preparation required by other non-destructive test methods, conducting MPT is relatively fast and easy.
Such flaws present in a magnetized part will cause a magnetic field to leave the part. If magnetic particles are applied to this surface, they will be held in place by the flux leakage to give a visual indication.