Magnetic Particle Inspection

Read more about our Magnetic Particle Inspection services below:

What is Magnetic Particle Inspection?

Magnetic particle Inspection (MPI) is a non-destructive testing (NDT) process for detecting surface and shallow subsurface discontinuities in ferromagnetic materials such as iron, nickel, cobalt, and some of their alloys.
The process puts a magnetic field into the part. The piece can be magnetized by direct or indirect magnetization.

How does Magnetic Particle Inspection Work?

Magnetic Particle Inspection is a fairly simple process, it involves running a magnetic current through the component that is being tested. Any flaws or cracks in the component will disrupt the flow of the magnetic current and causes magnetism to spread out from them. This creates a a flux leakage field at the site of the flaw.
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).
The second step of the process involves spreading metal particles over the component being tested. If there are any flaws on or near the surface of the component, the flux leakage field will draw the particles to the site of the flaw. This provides a visible indication of the approximate shape and size of the flaw in question.

Benefits of MPI:

  • Highly portable
  • Inexpensive
  • Doesn't need a stringent pre-cleaning operation
  • One of the best options for detecting fine, shallow surface cracks