As a portable non-destructive testing instrument, the magnetic particle flaw detector is widely used for the overall material inspection of steel structures, pressure vessels, pressure pipeline welds, plates, castings, and forgings. It can quickly and accurately determine the distribution of surface and near-surface crack defects in welds and materials. It should be noted that the magnetic particle flaw detector is only applicable to ferromagnetic materials and cannot be used for non-ferromagnetic materials.

The performance of the magnetic particle flaw detector determines the accuracy of the inspection results. To ensure the quality and safety of the inspection, it is necessary to test the performance of the magnetic particle flaw detector before inspection. According to the standards "JBT 7411-1994 Technical Conditions for Electromagnetic Yoke Flaw Detectors" and "JB-T 6870-2005 Technical Conditions for Portable Rotating Magnetic Field Flaw Detectors", the performance of the flaw detector is mainly tested by measuring its lifting force. The specific methods are as follows.

1. Pre-inspection checks

1.1. Before testing, inspect the appearance of the entire instrument to ensure there is no damage, and all component screws are tight;

1.2. All input and output cables should be clean and free of damage to ensure safety;

1.3. Check the probes supplied with the magnetic particle flaw detector to ensure that the A-type horseshoe probe and D-type yoke probe have movable joints that move and lock freely. Ensure that the wheels on the four feet of the E-type rotating magnetic field probe move freely;

1.4. Check the contact surface between the probe yoke and the workpiece; it should be flat and free of rust;

1.5. Check that the connection between the probe and the main unit is secure;

1.6. Check that the power supply voltage is normal;

2. Performance testing (using the CDX-1 AC/DC flaw detector as an example)

2.1. Testing the A-type probe: Prepare two iron discs, one weighing 7 kg and the other weighing 36 kg. Switch the main unit of the flaw detector to AC/DC mode sequentially. Open the A-type probe to about 100 mm pole spacing, align the probe yoke to the center of the iron disc (7 kg, 36 kg), press the switch button on the probe, lift the iron disc, and hold for 2-3 seconds.

2.2. Testing the D-type probe: Open the two yoke feet of the D-type probe and straighten them. Similar to the A-type probe, switch between AC and DC, and lift the two iron discs sequentially.

2.3. Testing the E-type probe: Prepare an iron disc weighing 17 kg. Ensure that the optimal air gap between the four magnetic poles of the rotating magnetic field probe and the workpiece is about 0.5 to 1 mm. (Adjusting the angle of the wheel bracket on the probe can change the air gap between the rotating magnetic field probe and the workpiece. If the air gap is too small, movement is difficult; if too large, sensitivity may be affected.) Ensure the main unit is switched to AC mode, and lift the 17 kg iron disc.