Why is surface preparation important in MPT?

Surface preparation is crucial in Magnetic Particle Testing (MPT) because it directly affects the effectiveness of the test. When the surface of the material is properly prepared, it ensures that any surface-breaking defects can effectively attract and hold the magnetic particles suspended in the testing medium. This adherence is essential for the visibility and identification of defects, as any contaminants such as paint, oil, rust, or dirt can interfere with the magnetic particles' ability to settle into the defect areas. Effective surface preparation allows for a clean and smooth surface, facilitating the penetration of the magnetic particles into cracks or discontinuities, thus enabling accurate detection of defects.

While factors such as aesthetic quality, magnetic field strength, and corrosion prevention are important in certain contexts, they do not play a direct role in ensuring that the magnetic particles adhere specifically to defect areas during testing. The primary focus of surface preparation in MPT is to maximize the likelihood of identifying flaws by ensuring an optimal interaction between the surface and the magnetic particles.