After the surface of the workpiece is coated with a penetrant containing fluorescent dye or coloring dye, the penetrant can penetrate into the surface opening defects under capillary action after a certain period of time, remove the excess penetrant on the surface of the workpiece, and then apply the adsorption medium-developer on the surface of the workpiece after drying. Similarly, under the capillary action, the developer will attract the penetrant in the defect, and the penetrant will seep back into the developer. Under a certain light source (black light or white light), the penetrant traces at the defect are displayed (yellow-green fluorescence or bright red).
(1) Applicable to the detection of defects with very small openings, extremely narrow gaps and visually difficult to detect on the surface of any non-porous material workpiece.
(2) Applicable to the detection of workpieces and products of various shapes, in production or in service.
(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 cracks, white spots, hairlines, folds, looseness, cold shuts, pores and slag inclusions on the surface of workpieces.
(2) It can detect surface defects of metal and non-metal workpieces. It is not limited by the chemical composition of the workpiece being tested.
(3) It can intuitively display the location, shape, size and severity of the defect.
(4) It does not require equipment, water or electricity, and is particularly suitable for on-site testing.
(5) It is not limited by the structure of the workpiece.
(6) It is not limited by the shape, size and direction of the defect. All defects opening on the surface can be detected at the same time with just one test.
(1) It cannot detect porous materials.
(2) It cannot detect defects that are not surface openings or that are blocked by external factors.
(3) The repeatability of defect detection is poor.
(4) It will cause certain pollution to the testing site.