Metal spraying manufacturers tell you that the program-controlled fluorescent magnetic particle flaw detector is used for the detection of various cracks, slag inclusion and other very fine defects on the surface and near surface of the workpiece caused by casting, forging, quenching, grinding, fatigue, etc.

The fluorescent magnetic particle flaw detector adopts a fixed and vertical structure to carry out AC fluorescent magnetic particle flaw detection for workpieces. It is suitable for nondestructive testing of parts made of ferromagnetic materials such as shafts, gears, discs and sleeves in machinery, automobile, military industry, aerospace, internal combustion engine, railway and other industries. It can find cracks and slag inclusion on the surface and near surface of parts due to casting, forging, welding, stretching, quenching, grinding and fatigue. In nature, magnetic lines of force always keep their continuity. When a ferromagnetic workpiece is placed in a magnetic field that saturates it, the magnetic lines of force are guided through the workpiece. If the magnetic line of force meets the discontinuities (such as cracks, slag inclusion, pores and other defects) on the workpiece material, the magnetic line of force will bypass these areas with low permeability (high magnetic resistance) and leak out of the workpiece surface, forming a "leakage magnetic field".

In this way, magnetic poles will be generated on both sides of the defect, and the magnetic powder (or magnetic suspension) will be absorbed around the crack and other defects. It can form obvious linear or point accumulation.

AC current has skin effect characteristics, the magnetic field intensity on the surface of the workpiece is higher than that inside, and the surface sensitivity is higher; The intensity of magnetic field produced by DC current on the surface of workpiece is equivalent to that inside, and the distribution of magnetic field is relatively uniform, which can detect the defects in a certain depth under the surface.