What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The function of the waterproof gasket is mainly to prevent the leakage of liquid or gaseous substances and the intrusion of external liquids, and has achieved the effect of sealing. Generally, the waterproof gasket is simply designed in the shape of a rubber ring plate.
1. Standards for fastener product dimensions: specify the content of the basic dimensions of the product; threaded products also include the basic dimensions of the thread, thread end, shoulder distance, undercut and chamfer, and the end of externally threaded parts size, etc. 2. Standards for technical conditions of fastener products. It mainly includes product tolerances, mechanical properties, surface defects, surface treatment, product testing standards and corresponding specific provisions. 3. Standards for screw product acceptance inspection, marking and packaging: specify the qualified quality level and sampling plan of random inspection items during product acceptance inspection, as well as product marking methods and packaging requirements. 4. Marking method standards for standard parts, fasteners, screws and screws: specify the content of the complete marking method and simplified marking method of the product. 5. Standards for other aspects of fasteners: such as standards for fastener terminology, standards for fastener product weight, etc.
Cross recessed pan head screws refer to cross recessed machine wire screws, which are represented by the letters PM. The country stipulates that the thread specification is M1.6-M10, the performance level is 4.8, A-50, A2-70, CU2, CU3 and AL4, H-type and Z-type cross recessed, and the product grade is Class A cross recessed pan head screws . If other technical requirements are needed, they should be selected from the current standards (such as GB/T196, GB/T3106, GB/T3098.1, GB/T3098.6 and GB/T3098.10).
Screws are a kind of fasteners commonly used in machinery, but most of the screws commonly used in the market are standard parts. The screws themselves are ordinary and have no function of preventing loosening and protecting the matrix. Therefore, in order to prevent the screws from loosening during use , Usually it is necessary to configure additional elastic washers, flat washers, etc. that are suitable for screws, and these elastic washers and flat washers are mostly metal products. During use, it is easy to wear with the body base and damage the protection of the sheet metal base. After long-term use, metal washers are easy to rust, which affects the tightening effect and appearance of screws. In addition, the use of metal washers not only increases the weight and cost, but also the assembly process is complicated and cumbersome, and the anti-loosening and anti-wear effects are not ideal. .
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