What are the causes of coating discoloration of precision automotive stamping parts?

2021-12-07 09:43:33

The galvanized surface of precision stamping parts is a little cyan white, and the luster is not very bright. Play the role of decorative effect.

Galvanizing is to coat a layer of zinc metal from several microns to more than ten microns on the surface of galvanized parts. It is an anodic coating for iron base, which has certain electrochemical protection, and galvanized parts have good rust resistance. Due to the electrochemical characteristics of zinc, it has a "sacrificial" protective effect on the steel matrix; The corrosion product (basic zinc carbonate) of the zinc layer in the atmosphere is relatively dense, well attached and insoluble in water, which has a certain protective effect on the zinc layer. Therefore, galvanizing is widely used to protect steel and its parts from atmospheric corrosion, especially for mass production of precision metal stamping parts.

The discoloration of precision automotive stamping parts has a certain relationship with the structural shape, the performance of plating solution and walking speed. In view of these factors, I'd like to talk about the solutions to the discoloration of plating on stamping parts.

For the structural shape, this is a physical phenomenon. It is impossible for us to change the structural shape of the workpiece for electroplating. Due to the characteristics of current, we can not change the current distribution of different parts of the workpiece in the electroplating process.

We can ignore this reason.

It's easy to solve this problem about the travel speed of the workpiece. As long as we adjust the speed regulator of the lead-in machine on the electroplating line to the appropriate speed. In this way, the coating thickness meets the standard and is evenly distributed, and the coating is not easy to change color.

The performance of plating solution is a key problem and an important starting point for us to solve the discoloration of workpieces. Therefore, when we choose the plating solution, we must repeatedly test and compare. Because the performance of the plating solution is transformed through a release, that is, the crystallization of metal ions on precision metal stamping parts. The crystal is fine, and the gap between the crystal nucleus and the crystal nucleus is small, so the protection ability of the coating is strong, that is, the corrosion resistance and oxidation resistance are strong, and the coating is not easy to change color.

On the contrary, if the crystal is rough, the gap between the crystal nucleus and the crystal nucleus is large, its protection ability is poor, and the coating is easy to change color. In this way, when we choose the plating solution, we should choose the plating solution with fine crystallization to electroplate the workpiece.