The Principle of Anti-loosening Nuts

The core principle of a self-locking nut lies in utilizing specific structural designs or material properties to prevent the nut from loosening spontaneously under conditions of vibration or shock, thereby ensuring the reliability of the connection. Its technical implementation primarily relies on the following three mechanisms:

 

Mechanical Locking Type: This method increases frictional resistance through special structures located either inside or outside the nut (such as nylon inserts or metal spring elements). For instance, in a nylon-insert self-locking nut, the nylon ring is compressed and deformed during tightening; this deformation fills the gaps between the threads, generating a counter-resistance force. Conversely, the metal-spring-element type prevents loosening by utilizing elastic components to exert pressure against the flanks of the threads.

 

Friction-Enhancing Type: This approach employs a double-nut configuration (such as a combination of a thin nut and a thick nut) or a specialized thread design (such as self-locking threads) to resist vibration by increasing the coefficient of friction at the contact surfaces. In a double-nut system, the upper nut applies a preload force to the lower nut, ensuring that the threaded joint remains under constant compression and thereby preventing it from coming loose.

 

Chemical Bonding Type: Some self-locking nuts feature an application of anaerobic adhesive on their threads; once tightened, the adhesive cures to fill the thread gaps, creating a permanent bond. This type is suitable for applications where disassembly is infrequent, though the adhesive must be reapplied if the nut is removed.