One, cadmium plating
The cadmium coating has very better corrosion resistance. Therefore, some manufacturers of hexagon socket bolts use cadmium plating to enhance the rust resistance of the bolts. However, the waste liquid generated during the cadmium electroplating process will be expensive when it is processed. It is more expensive, so it is more suitable for surface treatment of hexagon socket bolts used in airplanes and oil drilling platforms.
Second, sherardizing
Sherardizing is a more commonly used fastener surface anti-rust treatment process, which belongs to the zinc powder solid metallurgical thermal diffusion coating. Because of its good uniformity, it can be spread evenly in the threads and blind holes, and it will not pollute the environment during processing.
Three, electro-galvanized
Electro-galvanizing is also a common anti-rust treatment method for the surface of hexagon socket bolts, but because hydrogen embrittlement is more likely to occur during the galvanizing process, in order to maintain the consistency of the bolt pre-tightening force, lubrication can be applied after galvanizing Substance to enhance the torque of the bolt.
Four, chrome plating
The stability of the chromium coating is very good, and after chrome plating, the surface of the hexagon socket bolt will still maintain its luster, and it will increase the wear resistance of the bolt. Therefore, many decorative hexagon socket bolts use this type of surface to prevent rust. method.
