What effect does surface cleanliness have on MPT?

Surface cleanliness plays a crucial role in magnetic particle testing (MPT) because contaminants such as oils, dust, dirt, and other foreign particles can significantly interfere with the test results. When a surface is contaminated, it creates a barrier that prevents the magnetic particles from adhering properly to any discontinuities that may be present, such as cracks or voids.

This inhibition of particle adherence can lead to false negatives, where a defect may be present but is not detected simply because the magnetic particles cannot properly adhere to that area of the surface. Therefore, ensuring a clean surface before performing MPT is essential for obtaining accurate and reliable test results.

While improving visibility and enhancing magnetic fields can be positive effects under certain conditions, the primary concern is that surface contamination directly impacts the effectiveness of the magnetic particles in revealing flaws. Thus, a clean surface is vital for successful magnetic particle testing and for ensuring that potential defects are accurately identified.