A screw can be fitted with only one spring pad or only one flat pad, or it can be equipped with only one toothed two-piece assembly. The combination screw country number is indicated by GB9074. The commonly used cross recessed small head head three combination screw country code is GB9074.8. This .8 refers to the small head. This is also the size of the head of the pan head screw. Expressed in letters as PM. Professional combination screw manufacturers, the habitual representation method is triple PM. The commonly used cross recessed large pan head combination screw is GB9074.4. The professional is called the combination screw of the large pan head. Or R head, or B head. That is to say, the head of the combination screw is larger than the head of the small-head combination screw, and is thicker. Another commonly used one is the hex combination screw, which is a cross hex combination screw.
The combination screws are made of iron and stainless steel. Iron is made of different iron screws and wires. Generally, the wire of the combined screw is 1010, 1018, 10B21 or the like. 10B21 is used to make 8.8 combination screws. Like the 8.8-class hex combination screw, it is often used for 10B21 wire. After doing it, go to heat treatment. After the heat treatment, the hydrogen is removed and electroplated. This is to prevent the spring washer of the hexagon socket combination screw from breaking. Stainless steel combination screws, combination screws on the market, generally refer to stainless steel SUS304 combination screws. 201 combination screws are generally done very little. It is rare to combine the screw manufacturers to produce the combination screw of 201. Because the hardness of the screw wire of stainless steel 201 is not well controlled, it is easy to produce cracks.
The difference between the use of combination screws and ordinary screws is mainly in the wide range of applications. The use of common screws is more extensive than that of combination screws. Basically, industrial products use common screws and combination screws. It is useful for specific product materials. When the screw needs to be used with a spring pad and a flat pad, the combination screw can be used at this time.
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