Magnetic Particle (MT)
Our Inspectors perform magnetic particle inspection to detection of surface and subsurface defects in ferromagnetic materials (nickel, iron, cobalt, etc.)..
A magnetic field is placed onto the test object by direct or indirect magnetization and iron particles are drawn to where the flaw is located.
Direct magnetization occurs when the electric current is passed through the test object and a magnetic field is formed in the material.
Indirect magnetization occurs when no electric current is passed through the test object, but a magnetic field is applied from an outside source. The magnetic lines of force are perpendicular to the direction of the electric current.
The presence of a surface or subsurface discontinuity in the material allows the magnetic flux to leak since air cannot support as much magnetic field per unit volume as metals. Ferrous iron particles are then applied to the part. The particles may be dry or in a wet suspension. If an area of flux leakage is present the particles will be attracted to this area. The particles will build up at the area of leakage and form what is known as an indication. The indication can then be evaluated to determine what it is, what may have caused it, and what action should be taken if needed.
