Six types of bolt surface treatment and its process
Bolt surface treatment is a commonly used bolt processing, not only to improve the surface brightness of the bolt, the same can improve the performance of the bolt, that bolt surface treatment process are what?
1、Passivation
Bolt passivation treatment is in the passivation process will dissolve the iron pollutants hidden in the screws, so that the surface of the screws open into a layer of passivation of the protective film, can protect the bolt is not easy to be eroded by the corrosion of the general passivation of the surface treatment methods and methods applied to electronic products.
2、 oxidation (blackening screw fasteners blackened Oil coating is a very common plating for industrial fasteners. Because it is very cheap, it is cheaper than all the surface treatment. And it looks good before the oil runs out, but the blackened surface treatment basically has no rust resistance, so it will rust soon without oiling, even in the state of oil, its salt spray test can only reach 3-5 hours.
3、Electroplating
Plating on the surface of the bolt can enhance the bolt to carry the corrosion and erosion, but different types of plating layer can create a different degree of corrosion resistance. If you need to know how the degree of corrosion resistance, you can test the degree of corrosion resistance through the salt spray test.
Electro-galvanizing is the most commonly used surface treatment of screw fasteners, it is not only the lower cost, often galvanized after the appearance of screw fasteners is also more beautiful, can be plated into black, army green. However, zinc plating has a little bad, that is, its anti-corrosion performance is general, its anti-corrosion performance is the lowest in the plating (coating) layer, general zinc plating screws, through the neutral salt spray test within 72 hours, there is also a special sealant, so that zinc plating can be achieved after the salt spray test to reach more than 200 hours, but its price is expensive, is generally galvanized 5-8 times.
4、Surface phosphating
Screw fastener surface phosphating is cheaper than plating, but the corrosion resistance is poorer than plating, screw fasteners should be coated with oil after phosphating, because the corrosion resistance is high or low with the performance of the oil coated with a lot of great relations.
Screw fastener phosphating commonly used zinc phosphating and manganese yarn phosphating, zinc phosphating lubrication than manganese phosphating to be better than some manganese phosphating, manganese phosphating corrosion resistance and abrasion resistance than galvanized better, it is resistant to high temperatures of up to 225 degrees Fahrenheit to 400 degrees Fahrenheit (107-204 degrees Celsius).
Most screws and fasteners used in industry are phosphated and oiled because of their consistent torque and preload properties. In the assembly of parts to ensure that the design of the expected fastening requirements, so more used in industrial construction. Especially some important parts of the connection: some high-strength bolts using phosphating, but also to avoid hydrogen embrittlement. Therefore, in the industrial field, the bolts above 10.9 grade generally adopt phosphating surface treatment.
5、Electrophoresis
Electrophoresis surface treatment is the use of electrophoresis technology to paint, latex, rubber and other particles evenly covered to the surface of the bolt fasteners. After the surface treatment of electrophoresis, the plating layer on the surface of the bolt is plump, even, flat and smooth.
6、Spraying paint
Use spray gun to spray a thin layer with color on the bolt fasteners evenly, turn the bolt into more different colors, mainly used to beautify the appearance of the bolt. Spray paint is also mainly used in the electronics industry.
The surface treatment method of customized bolt processing should be based on the demand to choose the appropriate surface treatment method. Precision bolt manufacturing process requires more accurate, in the tolerance requirements, size requirements and other aspects are very high.