Methods for Preventing Loosening of Fasteners

The reasons for loosening of fasteners during use vary due to their different connection methods .So in practical use, appropriate anti loosening methods should be selected based on the anti loosening method of the fastener. There are currently several commonly used anti loosening methods.

Ⅰ Mechanical anti loosening.

It refers to applying force on the connecting surface to cause relative movement of bolts and nuts, thereby achieving the purpose of preventing loosening.

1.Slotted nut and split pin anti loosening:After tightening the nut, insert the split pin into the nut slot and bolt tail hole, and pull the split pin tail open to prevent relative movement between the nut and bolt.

2.Tandem steel wire anti loosening :Thread low-carbon steel wire into the holes on each screw head and connect the screws in series to brake each other.

Ⅱ Friction anti loosening.

It is achieved through the relative sliding between the threaded pair and the friction pair of the fastener to prevent loosening.For example, using spring washers, double nuts, self-locking nuts, etc.


1.Spring washers anti loosening:The anti loosening principle of spring washers is that after pressing the spring washer flat, the spring washer will generate a continuous elastic force, which will maintain a frictional force between the threaded connection pair of the nut and the bolt, generating a resistance torque to prevent the nut from loosening.

2.Double nuts anti loosening : Use the nut to exert additional tension and friction force in the bolt type to prevent loosening.

3. Self-locking nut anti loosening: One end of the nut is made into a non circular closure or a radial closure after opening. After the nut is tightened, the closure expands and the elastic force of the closure is used to compress the threads .This method is simple and reliable.

Post time: Aug-01-2023