What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
In many national standards, there will be a division of intensity levels. Combination screws are no exception. The strength grade of the combined screw is divided according to the material of the screw wire and the hardness index of the screw wire. General combination screw materials are divided into stainless steel and iron, stainless steel is divided into stainless steel 201, stainless steel 304 and stainless steel 316 and so on. Iron is divided into three types: low carbon steel, medium carbon steel, and high carbon steel. Carbon steel combination screws refer to iron combination screws. Generally, iron combination screws are classified into grades 4.8, 8.8, 10.9, and 12.9. However, the combination screws of grade 10.9 and grade 12.9 are rarely used in the market, so we will not talk about them here. And the combination screws on the market are more commonly used combination screws of grade 4.8 and 8.8. 4.8 grade combination screws are generally made of 1010A screw wire rods. After the screw wire rods are beaten into screws, they are combined with spring flat washers. After production, this 4.8 grade combination screw does not need to be hardened. Its hardness can reach 4.8. 8.8 grade combination screws are generally made of screw wire 10B21 piers. After the screw and wire piers are made into screws, they are equipped with spring washers and flat washers. They can pass through the automatic elastic flat washer machine to rub the three pieces together. Fasten the spring-flat washer combination on the screw, and the spring-flat washer will not fall off. After the combination screw is produced, it needs to be hardened to make the hardness reach 8.8. After the hardness reaches 8.8, we need to take it for electroplating. In order to prevent hydrogen embrittlement of the spring washer in the 8.8-level combination screw with added hardness, it is easy to break. In this way, we have to perform hydrogen removal treatment on the hardened combined screws, and only after the hydrogen removal can be plated. In short, there are many kinds of standard grades of combined screw strength, but generally only two types are used in the market, one is the 4.8-level combined screw strength, and the other is the 8.8-level combined screw strength. 4.8-level combination screws are the most used in the market and customer needs, and have a wide range of applications. As for the standard strength of 8.8-level combination screws, we generally refer to 8.8-level hexagon socket head combination screws, 8.8-level pan head combination screws, and 8.8-level external hexagon combination screws. These three are more commonly used.
Screws are a common type of fastener on the market. It is a type of fastener consisting of a head and a screw. It can be divided into three categories according to its purpose: machine screws, set screws and special purpose screws. Machine screws are mainly used for a fastened connection between a part with a fixed threaded hole and a part with a through hole, without the need for nut matching (this connection form is called screw connection, which is also a detachable connection; it can also be Matching with nuts, it is used for fast connection between two parts with through holes.) Set screws are mainly used to fix the relative position between two parts. Special purpose screws, such as eyebolts, are used for hoisting parts.
The slotted nut needs to be fixed with a cotter pin through the slot of the slotted nut, and the cotter pin must pass through the middle of the screw to fix the slotted nut. Usually, both ends of the screw need to be drilled, the diameter of the hole and the size of the slotted nut. The width and depth of the slot determine the size of the cotter pin. When the selected screw, cotter pin and slotted nut are relatively matched, the nut is fixed by the screw, so that the slotted nut does not loosen. This hexagonal slotted nut has the characteristics of high strength and is not easy to loosen when subjected to vibration. It is mainly used in occasions with vibration and shock, such as front and rear axles of automobiles, lifting equipment, presses and die-casting machines.
Knurled copper nuts are widely used in the following fields: notebook computer plastic casing, desktop computer plastic casing, GPS plastic casing, router plastic casing, mobile phone plastic casing, infinite communication facility plastic casing, home appliance plastic casing, automobile, electrical appliances, medical, electronics, etc. plastic shell.
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