Surface treatment is the whole process of producing a soil layer on the surface of the workpiece according to a certain method, and its significance is to endow the product with a beautiful surface. The actual effect of corrosion resistance, the surface treatment methods of fasteners are all attributed to the following methods: 1. Electroplating. Electroplated metal material is allowed to precipitate and deposit on the part. Generally, electroplating includes hot-dip galvanizing, copper, nickel, chromium, copper-nickel alloy, etc., and sometimes blackening (bluening) and phosphating treatment are also involved. 2. Hot-dip galvanizing is carried out by immersing carbon steel parts in a bath of molten zinc at a temperature of about 510°C. The effect is that the iron-zinc alloy material on the surface of the cast iron gradually becomes the passivated zinc on the outer surface of the product. Hot-dip aluminizing is a similar process. 3. Mechanical plating impacts the surface of the product through the particles of the coated metal material, and sprays the coating onto the surface of the product. Generally, the electroplating method is mostly used for screws, but hot-dip galvanizing is used for electric power engineering, high-speed roads and other outdoor hexagonal wood screws; the cost of electroplating is generally 0.6-0.8 yuan per kilogram, and hot-dip galvanizing is generally 1.5-2 yuan / kg, the cost is higher.