Magnetic Particle Inspection

Magnetic particle inspection is a preventive maintenance examination method of locating and revealing discontinuities in magnetic materials, at or near the surface, and those too small to detect with the naked eye.

This technique may be applied to raw, semi finished or finished materials. In weld applications, this technique also reveals defects such as incomplete fusion, undercut and inadequate penetration. This technique is particularly valuable under circumstances where ultrasonic or radiographic techniques cannot be used.

The magnetic particle method is based on the principle that magnetic field lines when present in a ferromagnetic material will be distorted by a change in material continuity. In the presence of discontinuities, the flux lines will be distorted. Under the magnetic field thus created, a magnetic powder dusted onto the surface will display a pattern over the discontinuity. Under proper lighting conditions, the accumulated particles in those locations will be visible.

Wet and dry magnetic powders can be used in this nondestructive method, depending on the application. The powder particles are colored, for improved visibility. Fluorescent powders are usually selected for increased sensitivity.

Magnetization of a ferromagnetic material can be achieved by applying an electric current through the material or by placing the material within a magnetic field.

Our magnetic Particle (wet, dry) inspection instrumentation is the following: