Magnetic Particle Testing (MT)
Magnetic particle testing (AKA Magnaflux) is a method of locating surface, or near surface, defects in ferromagnetic materials. Many drawings and codes call for Magnetic Particle Testing of castings, welds and forgings. The item to be tested is magnetized using an electrical current. While the item is being magnetized, iron powder is applied to the test piece. If there is a defect such as a crack, this creates additional magnetic poles which attract the iron powder. This iron powder is treated with a dye that makes it easily detectable, glowing green directly over the defect.
The particles are treated with a visible dye, which can be seen with ordinary lighting, or fluorescent dye, which requires the use of ultraviolet lights. We use the fluorescent particles whenever possible due to the increased sensitivity. This greatly increases the probability of detection (POD).