NDT Magnetic Particle Explained in English
Please note this is a free MT Magnetic Particle training review for a non-technical look at the NDT method in reference to nondestructive testing. Some terms in this article might not be NDT industry appropriate and other things are simply skipped. For a true NDT magnetic particle course per SNT-TC-1A or NAS-410 or CP-189 contact an NDT training facility and schedule your MT Magnetic particle classroom training, something we can easily accomplish for you. (shameless plug).
Magnetic particle is often called Magnaflux, MPI, MT, yoke check, or coil check. They are all essentially the same thing being that Magnaflux is a name brand www.Magnaflux.com. MT Magnetic particle is commonly used in the aerospace, amusement park safety, lifting device inspection chemical and petrochemical facilities and power generation industries. MT is part of the Nondestructive testing field.
So what is magnetic particle in NDT? In simple form, you are taking a part which is ferrous in nature (attractable by a magnet) and magnetizing it. By magnetizing the part you are making any opening or void on the surface or close to the surface its own little magnet, having its own attraction strength due to the leakage field which it has created. This little magnet or leakage field is then found by applying an iron particle (small shavings of iron) to the surface and seeing where they are attracted to the opening or crack.
MT – Magnetic particle testing may only be performed on ferrous materials. Keep in mind that a conductive material and ferrous materials are two different things. The selection of the process is normally broken down into circular or longitudinal, visible or fluorescent MT. When inspecting critical components, the fluorescent method is usually selected because of its contrast value of inspecting in darkness. Visible MT Magnetic particle is normally utilized for field applications of weld inspections.
When we say fluorescent MT we are saying that the inspection needs to be performed in a darkened room with a black light because the iron particles are fluorescent in nature and will light up when excited by a black light. Visible particles are simply visible and the inspection can be performed under normal lighting or a flashlight. A key component of both methods is lighting requirements.