Common Treatment Methods For Screws And Bolts

- Nov 17, 2020-

Screws have to undergo surface treatment during production and processing. What is the surface treatment? Surface treatment is the process of forming a covering layer on the surface of the workpiece through a certain method. Its purpose is to give the product surface a beautiful and anti-corrosion effect. The surface treatment methods carried out are attributed to the following methods:


    1. Electroplating: Immerse the electroplated parts in an aqueous solution containing the metal compound to be deposited, and pass current through the plating solution to precipitate and deposit the electroplated metal on the parts. Generally, electroplating includes zinc, copper, nickel, chromium, copper-nickel alloy, etc. Sometimes boiling black (blue), phosphating, etc. are also included.


    2. Hot-dip galvanizing: The carbon steel parts are immersed in a molten zinc plating tank with a temperature of about 510℃. The result is that the iron-zinc alloy on the surface of the steel gradually turns into passivated zinc on the outer surface of the product. Hot-dip aluminum plating is a similar process.


    3. Mechanical plating: impact the surface of the product through the particles of the coated metal, and cold weld the coating to the surface of the product.


    Generally, screws are mostly electroplated, but hot-dip galvanizing is used for outdoor hexagonal wood screws used in electric power, highways, etc.