The basic sheet metal processing flow for galvanizing (EG) electroplating involves pre-plating the parts, followed by degreasing, erosion, polishing, galvanizing, paint stripping, and passivation/dyeing. When you electroplate something, you can make a dense, uniform galvanized layer with a clean surface, a thin oxide film, more surface activity than phosphating, good flexibility, and high corrosion resistance. The uniformity of coating quality is better than hot-dip galvanizing, but the thickness of coating is not as satisfactory as hot-dip galvanizing. Because of its high surface quality, it is suitable for the exterior panels of passenger car bodies.
(2) The production process for hot-dip galvanizing (GI/GA) used in sheet metal processing is as follows: The process for pre-plated parts includes degreasing, water washing, acid washing, water washing, pressing, solvent coating, drying, galvanizing, cooling, straightening, oiling, and packaging.
In hot dip galvanized iron alloy (GA), the iron in the cold-rolled matrix of GI products diffuses into the zinc layer through the heat treatment process. This creates a zinc iron alloy with about 10% iron that is resistant to corrosion and has a multi-layer phase structure that makes the coating stick better and be easier to weld. After phosphating, the coating surface has excellent corrosion resistance under the film, but there are common pinhole defects.
The flow of sheet metal processing for mechanical galvanizing is described in detail. Different processes mainly involve different methods for establishing the base layer and thickening the coating, which can be roughly divided into two types.