Magnetization using the 4-pole method with direct current flow
(Testing & Demagnetization)
With the 4-pole method (see Figure 1) the test currents flow crosswise through the component in alternating directions. The DC pulses generated by the MT test device are passed into the component via test cables and magnetic poles (see Figure 3). Magnetic fields develop along the current paths. The leakages occurring at the cracks make for a clearly defined accumulation of magnetic particles and result in precise and clear crack images.
The 4-pole method is particularly suitable for magnetizing large-surface components (see Figure 2) and is used for both MT testing as well as demagnetization.