The most significant factor impacting the visibility of defects detected by Magnetic Particle Inspection (MPI) is the intensity of the magnetic field applied. A higher magnetic field intensity enhances the sensitivity of the inspection process, allowing for minute defects to be detected more easily. When the magnetic field is strong enough, it can better attract and hold the magnetic particles near the surface of any detected discontinuities, making these defects more visible.
If the magnetic field intensity is too low, the magnetic particles may not effectively aggregate at the flaw sites, leading to possibly missed defects or a delay in their detection. A robust magnetic field allows for a clearer contrast between the defect and the surrounding material, which is crucial for accurate evaluation.
While the color of the magnetic particles and the size of the part can influence the detection process, they do not have as direct an impact on the visibility of defects as the magnetic field intensity. The time of day, although it might affect lighting conditions, does not affect the fundamental detection capability of the MPI method itself.