MAGNETIC PARTICLE INSPECTION IS PERFORMED IN FOUR STEPS:
1. Magnetization: The first step in magnetic particle inspection is to magnetize the object being inspected. This can be done by either applying a current through the object or by using a magnetic field to induce magnetism in the object. The purpose of magnetization is to create a magnetic field within the object, allowing magnetic particles to be attracted to any surface defects or discontinuities.
2. Application of Magnetic Particles: Once the object is magnetized, magnetic particles are applied to the surface of the object. These particles are usually suspended in a liquid or powder carrier, which allows them to flow easily over the surface of the object. The magnetic particles are typically ferromagnetic, meaning they have the ability to be magnetized in the presence of a magnetic field.
3. Inspection: After the magnetic particles have been applied, an inspector will visually inspect the object for indications of defects or discontinuities. These indications appear as clusters or lines of magnetic particles, indicating the presence of a surface defect or crack. Different types of defects will produce different patterns of magnetic particles, allowing the inspector to identify the type and severity of the defect.
4. Cleaning and Demagnetization: Once the inspection is complete, the magnetic particles must be removed from the object. This is typically done by rinsing the object with a cleaning solution or using a special cleaning technique such as wiping or air blasting. After the particles have been removed, the object may need to be demagnetized to remove any residual magnetism. Demagnetization is important to prevent future attraction of magnetic particles and to ensure the object returns to its original magnetic state.