Grade4.8/8.8/10.9/12.9 High Quality DIN933 Bolts And Nuts
Description of Products
Bolts are divided into eight grades: 3.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9 according to their performance grades. Among them, bolts of grade 8.8 and above (including grade 8.8) are made of low carbon alloy steel or medium carbon steel and are heat treated (quenched). + Tempering), generally referred to as high-strength bolts, generally referred to as ordinary bolts below 8.8 (not including 8.8).
Nuts are parts that tightly connect mechanical equipment. Through the inner thread, nuts and bolts of the same specification can be connected together. It has Self-locking nut, lock nut, lock nut, four-claw nut, screw-in nut, safety nut, thin rod screw connection nut, self-locking hexagonal cap nut, special anchor nut, hexagonal crown thin nut, ring nut .
Bolt passivation treatment is to dissolve the iron contaminants hidden on the screw during the passivation process, so that the surface of the screw is opened into a passivation protective film, which can protect the bolt from being corroded and corroded. Generally, the passivated surface The processing method is applied to electronic products.
2. Oxidation (blackening)
Blackening of screw fasteners Oiling is a very common coating for industrial fasteners. Because it is very cheap, it is cheaper than all surface treatments. And it looks good before the oil runs out, but the blackened surface treatment basically has no anti-rust ability, so it will quickly rust without oil. Even in the oily state, the salt spray test is only It can reach 3-5 hours.
The torque and pre-tightening performance of the screw fasteners after blackening treatment is also very poor. To improve the consistency of the torque and pre-tightening force, it is only necessary to apply grease on the internal thread during assembly and then screw it together.
Electro-galvanizing is the most commonly used surface treatment method for screw fasteners. Not only is the cost low, the appearance of the screw fasteners that are often galvanized is also more beautiful, and can be electroplated into black or army green. However, there is one disadvantage of electro-galvanization, that is, its anti-corrosion performance is general, and its anti-corrosion performance is the lowest in the electroplating (coating) layer. Generally, the screws after electro-galvanization can pass the neutral salt spray test within 72 hours, and there are The use of a special sealant enables the salt spray test to reach more than 200 hours after electrogalvanizing, but its price is expensive, 5-8 times that of general galvanizing.
4. Surface phosphating
The surface phosphating of screw fasteners is cheaper than electroplating, but the corrosion resistance is worse than that of electroplating. Screw fasteners should be coated with oil after phosphating, because the level of corrosion resistance and the performance of the oil applied have a lot of big differences. relationship.
The commonly used phosphating of screw fasteners are zinc phosphating and manganese yarn phosphating. Zinc phosphating has better lubricity than manganese phosphating, and manganese phosphating has better corrosion resistance and wear resistance than galvanized ones. Better, its resistance to high temperatures can reach 225°F to 400°F (107-204°C)
Electrophoresis surface treatment is the use of electrophoresis technology to evenly cover paint, latex, rubber and other particles on the surface of bolt fasteners. After the surface treatment of electrophoresis, the plating layer on the surface of the bolt is full, uniform, flat and smooth.
6. Spray paint
The spray gun is used to spray a thin layer of color on the bolt fasteners to change the bolts into more different colors, which is mainly used to beautify the appearance of the bolts. Spray paint is also mainly used in the electronics industry.
7. Hot-Dip Galvanizing
The hot dip galvanized main advantages are good solderability and suitable contact resistance. Due to its good lubrication properties, cadmium plating is commonly used in aviation, aerospace, marine, and radio and electronic products. The plating layer protects the steel substrate from both mechanical and chemical protection, so its corrosion resistance is much better than zinc plating. Hot-dip zinc has good corrosion resistance, sacrificial protection for steel substrates, high weather resistance, and resistance to salt water erosion. It is suitable for chemical plants, refineries and coastal and offshore operating platforms.