Magnetic Particle Testing is a process for detecting surface and slightly subsurface discontinuities in ferromagnetic materials.

The process puts a magnetic field into the part. The piece can be magnetized by direct or indirect magnetization. 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 which may be either alternating current (AC) or some form of direct current (DC) (rectified AC).

Part can be magnetized by using Magnetic Yoke, Prode or Coil.

White light is used for visible Magnetic Particle testing and Ultraviolet light (UV light) use for Fluorescent Magnetic Particle testing. The sensitivity is highest for Fluorescent Magnetic Particle testing.