Magnetizing Current

Magnetizing creates a magnetic field in the workpiece. When you apply a testing medium, like magnetic powder, it collects where the field is disturbed, i.e., at cracks or defects. You need to magnetize the part so the field runs across the expected crack, otherwise you won't see the flaw. The current must be strong enough to saturate the workpiece cleanly, but not so high that you burn the surface or smear the indication. Make sure the field direction is right and, if in doubt, check with a second direction, then you'll have a reliable result.