Quick and Easy Technique to Detect Surface and Subsurface Flaws

Magnetic Particle Inspection (MPI) is a non-destructive testing method that can be used to detect surface and subsurface flaws in ferromagnetic materials. MPI is often used to find the job’s fitness for use & conformity. Since it is a Quick & relatively easy technique, it is widely used in various sectors including aerospace, automotive, petrochemical, structural steel and power generation in order to inspect a variety of products and equipment such as engine, suspension and braking system components, castings, forgings and weld joints.

A yoke has an electric coil in the unit creating a longitudinal magnetic field that transfers through the legs to the examined part. The yoke technique is easy to use with minimal training. It can be used indoors, outdoors, inside vessels and tanks, and in all positions. Yoke method is the MPI Technique widely used for on-site inspections.

ADVANTAGES OF MAGNETIC PARTICLE INSPECTION

One of the main advantages of using MPI is it gives instant indications 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.

• Quick and relatively uncomplicated
• Immediate indications of defects
• Shows surface and near surface defects
• Easily adapted for site or workshop use