Which materials can be effectively inspected using MPI?

Magnetic Particle Inspection (MPI) is a non-destructive testing method that is specifically effective for ferromagnetic materials, which include iron, cobalt, and nickel. The principle behind MPI is based on the way these materials react to magnetic fields. When a ferromagnetic material is magnetized, any surface or near-surface defects such as cracks, seams, or inclusions can disrupt the magnetic field, allowing magnetic particles to accumulate at these discontinuities. This creates a visible indication, highlighting the defects that need to be examined.

Ferromagnetic materials possess the necessary magnetic properties that allow them to be magnetized effectively. Other materials listed, such as aluminum, copper, plastics, rubber, and composites, do not have these ferromagnetic properties. They either do not respond to magnetic fields or do so in a way that does not allow for effective inspection using MPI. Thus, MPI is not suitable for non-ferrous materials or other non-magnetic substances, making ferromagnetic materials the ideal choice for this inspection method.