What factors influence the sensitivity of MPI?

The sensitivity of Magnetic Particle Inspection (MPI) is greatly influenced by several key factors, particularly particle size, concentration, and the strength of the magnetic field.

Particle size is crucial because smaller particles can penetrate tighter cracks and defects, making it easier to detect flaws that are less visible to the naked eye. Fine particles have a greater surface area-to-volume ratio, which enhances their ability to accumulate at discontinuities, thus increasing the likelihood of indicating a defect.

Concentration refers to the density of magnetic particles within the medium. A higher concentration increases the chances of sufficient particles being attracted to and accumulating at a defect site, which helps in achieving better contrast in the indicator.

The strength of the magnetic field is also a significant factor. A stronger magnetic field can better attract the magnetic particles, thereby enhancing their ability to cluster at defects. This leads to improved visibility of indications, which is essential for accurate inspections.

While ambient temperature and humidity levels can affect the overall process of MPI by potentially influencing the behavior of the particles or the magnetic field, they do not directly impact the inherent sensitivity of the technique itself. Additionally, the color of magnetic particles does not influence sensitivity; rather, it is a matter of visibility against the surface being inspected.

This analysis underscores why the