Alternating Magnetic Field Particle Inspection
Magnetic particle alternating field testing magnetizes parts with an alternating field and detects surface cracks through the skin effect. It enables fast surface inspection.
Physicochemical Mechanism of Action
Magnetic particle alternating field testing uses an alternating field to magnetically polarize metals. The alternating field induces magnetic flux lines that highlight surface cracks and defects. The skin effect ensures that the magnetic field is strong at the material surface and weakens with increasing depth.
Metallurgical Relevance & Welding Risks
This test is especially sensitive to surface cracks and defects. However, it can also produce false positives if the material is not magnetized homogeneously or if it is too contoured. Misinterpretations can lead to inaccurate conclusions.
Workshop Practice & Action Instructions
To perform the test successfully, the material must be clean and dry. The alternating field should be operated at a frequency of 50-60 Hz. The magnetic particle density should be between 200 and 400 mg/cm². The inspection time typically ranges from 10 to 30 seconds per component. In doubtful cases, additional tests such as radiographic testing should be performed.