Magnetic Particle (MT) is induced in the object. Iron fillings are then dusted onto the surface of the object being tested. If there is a defect, the fillings will cluster along the edges of the flaw. Variations include wet suspension and dry particle.

Advantages

• The training is less demanding that UT, RT or ET training.
• MT is quick and cost effective.
• The results are instant and easy to interpret.
• Positive and reliable method of testing.
• Surface preparation not as critical.

Disadvantages

• Only effective in ferromagnetic materials.
• Discontinuity detection is limited to at or near surface.
• Parts need to be de-greased and de-magnetized before and after inspection.
• Magnetic flux must be normal to the plant of the defect to show indications.