Dye penetrant inspection for appearance quality of impeller castings

Due to the thin and large number of impeller blade castings, in order to further inspect the surface and near surface of impeller blade castings, the joint between spokes and hub and rim, impeller blade castings and tooth roots for cracks, cold shuts, shrinkage porosity, shrinkage cavities and other defects, solvent removal dye penetrant testing process is adopted for flaw detection.

The first step is to clean the tooth root of the casting with cleaning agent to remove oil and dirt.

The second step is to spray the penetrant on the root of the tooth. The penetration time is 10-30min and the ambient temperature is 15 ℃. During the whole penetration time, the penetrant will always wet the surface of the workpiece and keep it dry.

The third step: after the penetration, wipe off the excess penetrant on the surface with a dry cloth, and then wipe it with a lint free cloth stained with remover. When wiping, wipe it in one direction.

The fourth step is to spray the developer on the workpiece surface. During spraying, the nozzle is 350mm away from the workpiece surface, and the included angle between the spraying direction and the workpiece surface is 35 ℃, so as to form a thin and uniform imaging layer with a thickness of 0.06mm.

The fifth step is to inspect under the white light after the imaging.

The inspection results are compared with GB / t9443-1988 penetrant testing of steel castings and grade evaluation of defect indications. The display length of linear or point linear defects is 1.5mm and the total length is 3.5mm, which meets the grade 01 standard and meets the service requirements of the workpiece.

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