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Hot - dip galvanizing process principle

Source:    Time: 2016-11-26

Hot-dip galvanizing process has a continuous galvanized (for strip or wire) and non-continuous galvanized (bulk galvanized for the cut-off profiles, structural parts, small pieces) two. Both processes require the presence of rust, scale, grease, coating residues, welding residues, molding sand residues on the castings, marking residue residues, etc. on the steel substrate.

The type of surface pretreatment method depends on the process and the type of product. It includes annealing (often used for continuous galvanizing), solution treatment (commonly used in bulk zinc), mechanical cleaning (sandblasting or shot peening), or a combination of solution treatment and mechanical cleaning. (Such as roller cleaning)

1, dry galvanizing process
Now dry galvanizing process is generally immersed in the workpiece before immersion in water-soluble auxiliary plating tank, and then hoisting to the drying furnace in the 60-120
temperature drying. The advantage of the dry galvanizing process is the convenience of plating large pieces and the surface of the plated parts without the aid of the plating residue.
2, wet galvanizing proce
In the ancient wet galvanizing process, a portion of the zinc bath surface is covered with a plating agent, just like a frame structure. The workpiece to be plated in the wet state through the help area into the zinc bath, dip plating bath surface from the zinc plating area without leaving. Wet galvanizing process has the advantage of the workpiece before the dip does not require drying to facilitate the plating of hollow type or pipe parts; drawback is the zinc bath in the AL mass fraction can not exceed 0.002%, or easy to produce coating defects (such as dark spots ). In addition, compared with dry galvanizing, wet galvanizing the amount of slag to be large.
The choice of process depends on the type of galvanized and the possibility of the device