What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The material of the combination screw is divided into iron and stainless steel. The iron ones are made of different iron screw wires. Generally, the wire of the combination screw is 1010, 1018, 10B21 and so on. 10B21 is used to make 8.8 grade combination screws. Like 8.8 grade hexagon socket head combination screws, 10B21 wire is often used. When done, go to heat treatment. After heat treatment, remove hydrogen and electroplating. This is to prevent the spring washer of the socket head cap screw from breaking. Stainless steel combination screws, in the combination screw market, generally refer to stainless steel SUS304 combination screws. 201 combination screws generally do very little. Few combination screw manufacturers produce 201 combination screws. Because the hardness of the screw wire of stainless steel 201 is not well controlled, it is easy to produce cracks.
As the requirements for the use of electrical appliances in various industries continue to increase, the testing specifications for the performance of various components in electrical appliances are also constantly improving. Riveted contact elements are used in various relays, contactors, small switches, thermostats, etc. in low-voltage electrical appliances. The structure of the riveted contact element generally includes a contact base and a rivet riveted to the contact base. The rivet includes a rivet head and a rivet top, the structure of which is shown in FIG. 1 .
When installing the ventilation duct, because the gap between the air duct and the wall and between the air duct and the air duct is deep and narrow, the arm cannot enter into it to operate, which brings about the installation of the screws and nuts at these positions. The following three methods are generally used: one is to directly break the wall for installation, but this method damages the building greatly, and cannot be used for the installation of screws and nuts in the gap between the air ducts; the other is to Set the inner flange in the air duct and connect it with bolts, which will reduce the effective cross-sectional area of the air duct and increase the resistance of the gas flow. Moreover, people need to enter the air duct for construction during installation. Considering the size of the air duct First, the supporting firmware with a high position and no force has certain hidden dangers; third, it is directly ignored and not done, but it is easy to cause the air duct connection is not tight and the air volume loss is large. The above-mentioned methods all have major construction defects, which not only waste a lot of manpower and time in the construction process, but also have the problem of low air supply efficiency.
Anti-corrosion technology Stainless steel screws are made of metal, and there are four main methods for metal anti-corrosion, namely the properties of the material itself, the environment of use, the interface between materials and the environment, and the improvement of the metal structure design. If a complete anti-corrosion alloy is used to make stainless steel Screws, unless there is a special need, are not cost-effective in terms of economics, and it is also impractical to completely isolate the appearance of the screw from environmental elements that can cause corrosion. Improving the metal structure design can improve the influence of special circumstances under certain conditions, but the design of most stainless steel screws cannot be fully corrected, and its maintenance effect is not permanent, so this method cannot basically solve the problem, as long as it is on the surface. Top anti-corrosion, that is, surface anti-corrosion treatment is the most widely used method. The anti-corrosion treatment on the surface of stainless steel screws refers to the use of various methods to apply a protective layer on the metal surface. The purpose of avoiding or mitigating corrosion. The protection layer should be able to meet the following requirements: 1. Corrosion resistance, wear resistance, high hardness, 2. The structure is tight, intact, and the pores are small. 3. It has strong separation and good adhesion with the base metal. 4. It is evenly distributed and has a certain thickness. The maintenance layer is usually divided into two types: metal coating and non-metallic coating. Metal coating refers to the use of metal or alloy with strong corrosion resistance to form a maintenance layer on the surface of metal that is easy to corrode. This coating is also called plating. There are quite a few methods and varieties to produce metal coatings, the most common of which is electroplating, followed by molten metal immersion plating (hot dipping) and chemical surface treatment. Non-metallic coating refers to the use of organic polymer materials such as paint and inorganic materials such as ceramics to form a protective layer on the surface of metal equipment or parts. The protective layer can completely isolate the base metal from the environmental medium and prevent the base metal from corrosion due to contact. Corrosion is formed in the medium of stainless steel standard parts.
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