The average temperature limit coating material to lower than fasteners, still need to consider working temperature of fasteners. For surface treatment, people generally attention is beautiful and anti-corrosion, but the main function is to tighten fasteners and components, and surface treatment of fastener tighten performance has great influence, so, choose the surface, also should consider to tighten performance, i.e. installation torque - the consistency of prestressing force. Since almost all mechanical hardware fastener industry is made from carbon steel, alloy steel, some kinds of fasteners, hope to be able to prevent corrosion, even the use of anti-corrosion materials fasteners, still need to surface treatment to prevent corrosion of different materials. A high level of designers, not only should consider the design, but also because of the assembly process, notice or environmental requirements. According to the above factors below are briefly introduced, and some of the commonly used in coating fastener design personnel and personnel fasteners. In addition, the surface treatment of the coating must adhere firmly, not in the installation and the process of thread fasteners, coating, need enough, after the plating thin thread can still screw.

Electricity galvanized

Electric galvanizing is the most commonly used mechanical hardware fastener industry of coating. It is cheaper, appearance is beautiful, can have black and military green. However, it is usually the anticorrosion performance, the anticorrosion performance is zinc plating (the lowest layer coated). General electric galvanizing ZhongXingYan fog test in 72 hours, also have special blocker, make ZhongXingYan fog test reach 200 hours, but the price is expensive, galvanized the 5 ~ 8 times.

Electricity galvanized process, so easy to produce hydrogen brittleness bolts above level 10.9 generally do not use galvanized coating processing. Although after drying oven can be used to, but because hydrogen passivation membrane in 60 degrees above will be damaged, so to hydrogen must be conducted before after plating passivation. So poor maneuverability, processing cost is high. In reality, the general factory won't go unless specific active hydrogen mandatory requirements. Customer

Electricity galvanized fastener torque - pre-tightening force consistency, and unstable, generally not used in important parts of the connection. In order to improve the consistency of torque - pre-tightening force, also can use after the plating coating lubrication method of material and improves torque - pre-tightening force consistency.