Magnetic Particle Inspection is use to examine surface and near surface imperfection. Magnetic Particle Inspection uses magnetic field and small magnetic particle ( iron filings ) to detect flaws in test object. By inducing a magnetic field in a Ferromagnetic material and then dusting the surface with iron filings, any surface flaw will be visibly show by a sharp line concentrated with iron filings that follow the path of crack.
Magnetic Particle Inspection is relatively fast and easy to apply. The flaw indication generally resembles the actual crack.
The surface must be clean and smooth any paint to be removed. The test object must be made of a Ferromagnetic material such as Iron, Nickel or some of their alloys.