Hot dip galvanizing technology
Defects such as welds, cracks, blisters, and wrinkles in the workpiece structure should be inspected, repaired, and cleaned during the preprocessing process.
These defects will cause liquid to remain in the pre-treatment process, which will affect subsequent processes. Especially in the drying process, if these defects contain plating flux, zinc explosion, missing plating, etc. will occur during the galvanizing operation.
After the workpiece is hot-dip galvanized, these defects will continue to contain water and passivation liquid. During the trimming process of the workpiece, the liquid in the defects flows on the surface of the galvanized layer, forming liquid flow marks, commonly known as "yellow soup", as shown in the figure.
The cleaning, grinding, trimming and gunning of "yellow soup" are one of the important contents of the surface quality inspection of the galvanized layer of the workpiece.
