How Do Anti-loosening Nuts Prevent The Nut From Coming Loose?

A self-locking nut is a type of fastener that has undergone a specialized anti-loosening treatment-often referred to as a "self-locking screw"-and is suitable for securing moving components. So, how exactly does a self-locking nut prevent itself from coming loose?

 

Prevention via Friction: This is a widely utilized method for preventing loosening. Through this approach, a positive pressure-one that remains constant regardless of external forces-is generated between the mating nut and bolt. This pressure creates friction, thereby preventing any relative rotation between the nut and bolt assembly. This positive pressure can be achieved by applying an axial force to the nut pair, or by applying force simultaneously to both components. Examples of fasteners employing this principle include elastic washers, double-nut systems, self-locking nuts, and insert-type anti-loosening nuts.

 

Prevention via Riveting, Punching, or Bonding: Once tightened, methods such as punching, welding, or adhesive bonding are applied. Consequently, the nut-and-bolt assembly loses its ability to function as a movable joint, and the connection becomes a permanent, immovable fixture. The drawback of this method is that the bolt becomes a single-use component; disassembly is difficult, and the fastener assembly must typically be destroyed in the process of removing the connection.