When a ferromagnetic workpiece is magnetized under the action of an appropriate external magnetic field, it generates a magnetic induction magnetic field. When there is a discontinuity on the surface or near the surface of the workpiece, the magnetic induction lines of the induced magnetic field will be locally distorted to generate a leakage magnetic field, which will adsorb the magnetic powder applied to the surface of the workpiece and form a visually visible magnetic mark under appropriate lighting conditions, thereby showing the location, size, shape and severity of the discontinuity.
(1) Applicable to the detection of defects on the surface and near the surface of ferromagnetic workpieces with very small dimensions, extremely narrow gaps and visually difficult to see.
(2) Applicable to the detection of unprocessed raw materials and processed semi-finished products, finished products, and in-service and used workpieces and products.
(3) Applicable to the detection of various components such as pipes, bars, plates, profiles, forged steel parts, cast steel parts and welded parts.
(1) It can detect defects on the surface and near the surface (open and non-open) of ferromagnetic materials.
(2) It can intuitively display the location, shape, size and severity of defects.
(3) It has high detection sensitivity. It can detect defects with a width of micrometer level.
(4) It has fast detection speed, simple process, low cost and light pollution.
(5) It is almost unaffected by the size and geometry of the workpiece.
(6) It has good repeatability of defect detection.
(7) When the coating of the workpiece is thin, it can be detected without removing the coating.
(8) It can detect defects such as cracks, white spots, hairline, folds, looseness, cold shut, pores and slag inclusions.
(1) It can only detect workpieces made of ferromagnetic materials.
(2) When magnetizing by channel method and contact method, arc is easy to burn the workpiece. The non-conductive covering layer of the electrical contact part must be polished off.