What is a common method to demagnetize a part after MPI?

Using an alternating current (AC) demagnetization process is a common method for demagnetizing a part after Magnetic Particle Inspection (MPI) because it effectively reduces the residual magnetism that may remain in a magnetic material after testing. The process involves passing an alternating current through a coil that generates an alternating magnetic field. This field changes direction and gradually reduces in strength, which helps to randomize the magnetization of the ferromagnetic particles within the part. As a result, the part is demagnetized effectively, making it safe for further processing or use.

This method is particularly effective because the alternating current causes the magnetic domains within the material to oscillate, ultimately leading to a neutralization of the magnetic field. It's a widely accepted practice in the industry due to its efficiency and thoroughness in achieving demagnetization without damaging the inspected part.

Other potential methods, while they may serve similar intents, do not provide the same level of effectiveness or practicality in most industrial applications. For instance, mechanical vibration may assist in breaking up surface layers but does not specifically target the internal magnetic domains effectively. The continuous direct current (DC) process generally magnetizes components rather than demagnetizes them. Similarly, although a magnetic field generator could theoretically be used, it