Magnetic Particle Inspection – MPI

Magnetic Particle Inspection or MPI is a process for detecting surface and subsurface anomalies in ferromagnetic materials such as iron, nickel, and cobalt. The process involves putting a magnetic field into the test object. Flaws will be detected when the magnetic field flowing through the test object is interrupted and there is flux leakage. Ferrous iron particles are then applied to the object in a dry or wet suspension, and will be attracted to the flux leakage. This step-by-step process includes: Pre-cleaning of test object (to ensure it is free of rust, dust, oil, and grease), introduction of magnetic field, application of ferrous iron particles, and interpretation of indications. MPI testing methods offered by Steel City NDTGround Penetrating Radar: The Unique Applications. Read more ... » LLC include:

  • Dry Magnetic Particle – Iron Oxide
  • Wet Fluorescent Magnetic Particle (oil or water based) – Iron Oxide
Wet Fluorescent Magnetic Particle Inspection and Test (Crack)

Wet Fluorescent Magnetic Particle Test (Crack)

Magnetic Particle Inspection (MPI) also utilizes either a Direct (DC) or Alternating (AC) current. Alternating current is most commonly used to detect surface discontinuities. Direct current is used to detect both surface and subsurface discontinuities. Direct current, however, is limited on very large cross-sectional parts in terms of how well the part is able to be magnetized. Magnetic Particle Inspection (MPI) can also be performed by utilizing several different pieces of equipment. Equipment includes:

  • Wet Horizontal MPI Machine – Mass production inspection machine that contains a head and tail stock, which has an induction coil centered between them. These are typically customized to a specific application.
  • Mobile Power Packs – Custom-built magnetizing power supplies which are used in wire wrapping applications such as coils.
  • Magnetic Yoke – Handheld device that induces a magnetic field between the two prods on the yoke. This is the most commonly used device for on-site Magnetic Particle Inspection (MPI). While performing the inspection, the yoke is rotated 90 degrees for each inspection area to detect both horizontal and vertical discontinuities.
Wet Fluorescent Magnetic Particle Inspection and Test (Crack)

Wet Fluorescent Magnetic Particle Test (Crack)