What are the steps for Dye Penetrant Testing (DPT) of copper bushing?

Dye Penetrant Testing (DPT) is a non-destructive testing method used to detect cracks, porosity and other small defects on the surface of copper bushings. It is used to detect cracks, porosity and other small defects on the surface of copper bushing by applying dye penetrant on the surface of copper bushing, utilizing capillary effect to make the penetrant enter into the surface defects, and then these defects will be revealed through the visualizing agent.

The basic steps of color flaw detection:

Surface Cleaning: Thoroughly clean the copper bushing of the workpiece to be inspected, removing contaminants such as grease, dirt and oxides to ensure that the penetrant can enter the surface defects smoothly.

Coating penetrant: The liquid penetrant (usually red or fluorescent dye) is coated on the surface of the copper bushing. The penetrant penetrates into tiny cracks or pores by capillary action.

Penetration Time: The penetrant needs to remain on the surface of the copper bushing for a certain period of time (usually a few minutes) to ensure that it has full access to all surface defects.

Removal of Excess Penetrant: After penetration of the penetrant has been completed, remove the excess penetrant from the surface of the workpiece using a cleaner or clean cloth, but be careful to retain any dye that has penetrated into the defects.

Apply developer: Spray a developer (usually a white powder) onto the surface of the copper bushing. The developer will adsorb into the penetrant on the surface, making the penetrant hidden beneath the surface visible and creating a contrasting image of the defect.

Observation and Evaluation: The surface of the copper bushing is observed by the naked eye or fluorescent light (if fluorescent penetrant is used) and the defects will appear as red or bright spots.

Cleaning the workpiece: After the inspection is completed, the surface of the copper bushing is cleaned and all probing material is removed.