What is the reason for magnetizing a steel part in multiple directions during magnetic particle inspection?

• A. To detect faults that extend across as well as lengthwise within the part.
• B. To increase magnetic flux for deeper penetration.
• C. To shorten inspection time.
• D. To reduce residual magnetism.

Answer: (A)

In magnetic particle inspection, defects disturb the magnetic circuit and cause leakage fields that attract the magnetic particles used for indication. A single magnetization direction will produce leakage most readily for cracks that run parallel to that direction. Defects oriented differently—across or at angles to the field—may not create a noticeable leakage signal if you only magnetize once. By magnetizing in multiple directions, you ensure that cracks of various orientations will intersect the magnetic flux and produce detectable leakage, revealing faults that extend across as well as along the part.