In MPI, what does the term "indication" refer to?

In Magnetic Particle Inspection (MPI), the term "indication" specifically refers to the visible response of magnetic particles that reveals a flaw in the material being inspected. When magnetic particles are applied to a surface that has been magnetized, they gather at the site of any surface or near-surface defects, such as cracks or inclusions. This gathering creates a contrast that makes the flaw detectable against the surface of the material, allowing inspectors to identify potential issues.

The clarity and visibility of these indications are crucial for assessing the integrity of materials, as they provide essential information about structural defects that may compromise safety. Understanding how these indications form and what they represent is fundamental for an effective MPI process, reinforcing the significance of monitoring and interpreting indications during inspections.