Magnetic Particle Inspection(MPI)

Magnetic Particle Inspection (MPI) is a non-destructive testing method that can detect surface and subsurface flaws in ferromagnetic materials.

Magnetic particle inspection is often carried out to help determine an item’s fitness for use or conformity. This quick and relatively easy to apply technique is widely used in all industry sectors including aerospace, automotive, petrochemical, structural steel, and power generation to inspect a variety of products and equipment such as engine, suspension and braking system components, castings, forgings and weldments.

The method can detect surface or near-surface flaws such as cracks, laps, seams and inclusions in ferromagnetic materials such as iron and steel. One of the main advantages of magnetic particle inspection is that it can give an immediate indication of defects and discontinuities.

The technique works by inducing a magnetic field in the component tested. If a surface or near- surface flaw is present, the magnetic flux is distorted and ‘leaks’ around the flaw. By dusting the surface of the tested item with fine magnetic particles such as ferrous iron filings, (applied either dry or suspended in liquid), the particles will be attracted to the area of the flux leakage creating a visible indication of the defect. The indication can be evaluated by the operator to determine what it is, what may have caused it, and what action should be taken, if any.

Our techniques for magnetic particle inspection include:

• Bench (Direct current/Head shot/Central Conductor/AC/DC)
• Permanent magnetic
• Yoke (AC/DC)
• Ring bench
• Coil/cable wrap technique
• Prod technique