Why is surface preparation important before conducting MPI?

Surface preparation is crucial before conducting Magnetic Particle Inspection (MPI) because it ensures that contaminants do not interfere with the detection of defects. MPI relies on the magnetic particle medium being applied to the surface of the test material; if the surface is contaminated with oils, dirt, rust, or other foreign materials, these contaminants can block the magnetic particles from adhering to surface defects. As a result, true defects may go undetected, leading to potential structural failure or safety issues.

By properly preparing the surface—such as cleaning it to remove any contaminants and ensuring it is free of moisture—inspectors can enhance the effectiveness of the MPI method. This preparation directly impacts the accuracy and reliability of the inspection results, ultimately ensuring that any flaws are correctly identified and properly evaluated.