How to prevent loosening of nuts and bolts

Update:22-06-2018
Summary:

1. Loosening is one of the major failure modes of threa […]

1. Loosening is one of the major failure modes of threaded fasteners. The loosening of threads has always been a serious problem in industrial manufacturing and industrial products. It is even a fatal hidden danger and has caused unpredictable damage to our daily life, work, transportation, and national defense military.

2. So how do we prevent it?

Anti-loosening of the threaded coupling must consider two requirements: first, it must be reliable, and second, it should be easy to disassemble for frequent disassembly and maintenance.

There are several types of anti-loose locks, mechanical locks, and material locks. The following types of anti-loose locks are commonly used: spring washers, spring washers, snap washers, double nuts, lock nuts, bolts with holes Slotted nuts plus split pins, adhesives, etc.Non-Standard Bolts

(Spring, elastic, stop) washers, relying on the embedment of the elastic force and its cut corners play a role in the prevention of loosening, but are not very reliable due to uneven elasticity, and are mostly used for less important joints, on the joint surface Scratches and frequent disassembly are not recommended.
4. The locking principle of the non-metallic insert lock nut is that when the external screw is screwed in, the lock force is generated due to the good elasticity of the nylon material. It can also be used to adjust the position when the vibration is not great. However, due to the limitation of the melting point of nylon, the maximum working temperature of this type of nut should be less than 120°, preferably less than 100°.

5. And the installation of non-metallic insert locknuts have the following problems: 1 to increase the tightening torque; 2 pairs of bolts are more stringent requirements, the length is appropriate, and the bolts must not have open pin holes and burrs (for bolts The processing accuracy is relatively high.)

6. Hole-bolt Slotted nut and cotter pin are suitable for loosening of important parts of variable load and vibration occasions. The performance is reliable, but the design and assembly are inconvenient.

7. The use of adhesive bonding screw thread, the method is simple, economical and effective. Its anti-loose performance is directly related to the adhesive. According to the relaxation torque and temperature conditions, as well as the requirements of detachable or non-removable, appropriate adhesives are selected.

8. Thread locking glue can provide different loose retraction torque (loose damage/disassembly torque), combined with customer's requirements, to achieve a perfect relaxation effect.