Magnetic particle inspection is one of the most reliable methods for detecting defects, which are near to the surface or outcrop to the surface in ferrous materials. The advantage of this type of test is its simplicity, making it a very cost-effective and efficient method.
Typical applications include inspections for fine defects in the surface of castings and forgings, as well as inspections of welded assemblies for surface cracks. Inspections can be carried out on-site with the aid of electro magnets on large or in-service components or in our laboratory. MT Testing usually requires electrical equipment to generate magnetic fields that will detect surface and near surface discontinuities in Ferromagnetic materials. Magnetic Particle testing is useful for ferromagnetic metals such as iron, nickel and cobalt. There are 2 methods, one is to apply with a permanent magnet the other method is using an electromagnet.
MT works best for flaws which are elongated rather than rounded. An internal magnetic field is generated and then tested. In locations where the flaws exist, (ie. non-magnetic voids), some of the field will leak off the specimen and bridge the voids through the air. However, because magnetic lines don’t travel well in air magnetic particles, dusted over the magnetized area are attracted to the leakage or the external fields. The magnetic particles could be a dry form of powder or held in a liquid solution. Their build-ups form a flaw indication.
The most accurate Magnetic Particle testing technique is when examinations are carried out in a Darkroom. Here we use a fluorescent light or UV light to view the particles which allows more clarity as the light is much more sensitive that regular light. This method is usually used for machine parts such as gear components and smaller machinery that can be taken into a darkroom.
Our specialist staff will then evaluate the Indication to understand what it is, the cause and if there is any action required. For more information or to discuss your requirements please contact Scanway NDT specialist