Service HotlineFasteners include: bolts, studs, screws, nuts, washers, pins. Locking or seizure often occurs on fasteners of stainless steel, aluminum alloy and titanium alloy materials. These metal alloys themselves have anti-corrosion properties. When the surface is damaged, a thin oxide layer will be formed on the metal surface to prevent further rust. When the stainless steel fastener is locked, the pressure and heat generated between the teeth will destroy the oxide layer, causing blockage or shearing between the metal threads, and then the phenomenon of adhesion occurs. When this phenomenon persists, the stainless steel fasteners will be completely locked and can no longer be removed or continued to lock. Usually this series of blocking_shear_adhesion_locking takes place in just a few seconds, so the correct understanding of the use of this type of fasteners can prevent this phenomenon.
① Nominal thread outer diameter (thread specification): divided into metric system and inch system. Metric thread → common specifications are 2; 2.3; 2.5; 2.6; 2.9; 3; 3.1; 3.5; 4; 4.2; 4.5; The unit is mm (millimeters). Inch thread→ Common specifications are 2#;4#;6#;8#;10#;12#;1/4;7/32;5/16;3/8;1/2 ;9/16;3/ 4. The unit is in (inches). ② Number of teeth/pitch: Definition of number of teeth → the number of teeth lines in one inch (25.4mm) length. Pitch Definition → Distance value between two adjacent threads. Conversion of number of teeth and pitch of teeth → pitch of teeth = 1 inch/number of teeth ③Nominal length: divided into metric system and inch system. Metric Nominal Length → Common values are 5, 6, 6.5, 7, 8, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 18, 19, 20, 21, 25, 28, 30, 31 , 32, 35, 40, 42, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120. The unit is mm (millimeters). Imperial Nominal Length → Common values are 1/4, 5/16, 3/8, 7/16, 1/2, 5/8, 3/4, 1, 2, 3. Units: in (inches). ④Head type: use letters to indicate the type of head type, please refer to the previous classification of commonly used screw head types. ⑤Tooth type/tail type: Use letters to indicate the type of tooth type/tail type, please refer to the previous Commonly used screw thread/tail type classification. ⑥Groove type: Please refer to the previous section Category of common screw groove types of our company. Cross-slotted or non-slotted (such as punched hexagon head screws) do not need to be marked here, and other groove types need to be described in words. ⑦Special labeling: In general, no labeling is required. When expressing its characteristics, it is described in words at this position. For example: the specification name of the screw is described as 4-0.7x70PM±tooth length 35, which means 4 is the nominal diameter of the screw thread, 0.7 is the pitch, 70 is the nominal length of the screw, and P means its The head type is a pan head, M means its tooth type/tail type is a wire thread type, ± means its groove type is ± groove and can also be expressed by plus or minus groove. Tooth length 35 is special Mark, specify the thread length value of this screw.
Surface treatment process of screws 1. Types of surface treatment: Surface treatment is the process of forming a covering layer on the surface of the workpiece by a certain method. The purpose is to give the surface of the product a beautiful and anti-corrosion effect. The following methods are as follows: 1. Electroplating: Immerse the part to be electroplated in an aqueous solution containing the metal compound to be deposited, and pass the current through the plating solution to precipitate and deposit the electroplated metal on the part. Generally, electroplating includes galvanized, copper, nickel, chromium, copper-nickel alloy, etc., and sometimes blackening (blue), phosphating, etc. are also included. 2. Hot-dip galvanizing: It is done by immersing the carbon steel parts in a zinc-melting bath with a temperature of about 510°C. The result is that the iron-zinc alloy on the surface of the steel gradually becomes passive zinc on the outer surface of the product. Hot dip aluminizing is a similar process. 3. Mechanical plating: The surface of the product is impacted by the particles of the plated metal, and the coating is cold welded to the surface of the product.
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.
The traditional fixture shown in Figure 2 is composed of a hardened support cylinder and a hardened shear bar, and has a simple structure. The cylindrical pin is loaded into the hardened support cylinder, and the shear test is completed by applying an axial load to the hardened shear bar. Since the standard stipulates that the gap between the loading part and the supporting part does not exceed 0.15mm, in order to ensure the matching of the gap during the shear test of the cylindrical pin, the diameter of the cylindrical pin on the cylinder is generally equal to the theoretical cylindrical pin. In practical application, the cylindrical pin is irregular in size after heat treatment. To realize the shear test, the cylindrical pin must be inserted into the hole with the help of external force, which is difficult to install and clamp and takes a long time. If the double-sided shearing is performed, that is If the cylindrical pins need to be installed on both sides, the time is doubled, and the notch of the cylindrical pins cannot be guaranteed to face upwards.
We have many years of experience in the production and sales of screws, nuts, flat washers, etc. The main products are: KM iron screws, special-shaped aluminum alloy nuts, metric high-strength screws, national standard 12.9 screws and other products, we can provide you with suitable fastening products piece solution.
