When a ferromagnetic workpiece is placed in a magnetic field, magnetic field lines are directed toward and through the workpiece. If the magnetic field lines act on the crack, the magnetic field lines will not be continuous and will overflow the surface of the workpiece, thus producing magnetic poles on both sides of the crack. Spray magnetic powder (or magnetic suspension) on the surface of the defective workpiece, and the magnetic powder will form an obviously visible line at the crack (Figure 1). The color of the magnetic powder should be chosen to have a greater contrast with the surface of the workpiece as much as possible, which will make it easier for defects to be observed by the human eye (this equipment uses fluorescent magnetic powder). This is the basic testing principle of magnetic particle testing.

1. Power supply: three-phase five-wire 50Hz 380V±10% 160KVA (maximum instantaneous);
2. Magnetization method: circumferential, longitudinal, composite magnetization;
3. Circumferential magnetizing current: AC: 0-8000A, continuously adjustable; with power-off phase control function. DC: 0~4000A half-wave average, continuously adjustable;
4. Longitudinal magnetizing current: AC: 0-16000AT, continuously adjustable; with power-off phase control function DC: 0-8000AT, continuously adjustable; with power-off phase control function
5. Coil inner diameter: Φ350mm
6. Detectable workpiece length: 4000mm;
7. Detectable workpiece diameter: ≦250mm;
8. Sensitivity: Magnetized according to the process specification JB/6965-92 "Standard Test Pieces for Magnetic Particle Flaw Detection Machines", the full circle and cross of type A sensitivity test piece 2# (15/50) can be clearly displayed;
9. Current duty cycle: not less than 25% at full load;
10. Magnetic field intensity on workpiece surface: ≥2400A/m;
11. Workpiece clamping rotation mode: electric;
12. Tail electrode movement mode: electric;
13. Electrode clamping method: pneumatic;
14. Working mode: manual and automatic;
15. Loading and unloading methods: manual;
16. Air source pressure: 0.4-0.6Mpa;
17. Demagnetization method: circumferential and longitudinal automatic attenuation demagnetization, which is convenient and fast;
18. Demagnetization effect: residual magnetism ≤ 0.2mT (3Oe);
19. Ultraviolet illumination: ≥4500uw/cm2 at a distance of 380mm from the light source;