4 Major Causes of Loose Nuts And Bolts

4 Major Causes of Loose Nuts And Bolts

27 April 2020
 Categories: , Blog

The safe operation of many tools in various industries relies on the use of a bolted joint. Most industries, such as transportation and manufacturing, choose to use bolts and nuts since they are easy to dismantle. But that also means they have a high chance of self-loosening. Bolt loosening can lead to profound consequences depending on the application of the bolts. A single loose bolt can pose a safety hazard or stop the whole production in a company. 

Here are the top causes of loose bolts and nuts.


The conditions under which the bolts operate can make them get loose. Some applications can cause shaking of the nuts. Vibrations lead to a parallel movement of the two connected joints and the bolts. Such repeated actions work against the friction between the joints and the bolts. After some time, the bold unwinds from the mating threads. Thus, the clamping force of the joints reduces. 

Gasket Creep

Most nuts and bolts include a thin and flexible gasket. The purpose of the gasket is to completely seal off the joint and prevent gas or liquid leaks. The device is usually between the bolt head and the joint surface. It works like a spring, pushing back the pressure from the joint and bolt. But the gasket may creep after it's used for some time. 

Creeping of the gasket means that it loses the springiness. That consequently causes it to lose its clamp force. A gasket creep can also happen if the tightening of the bolt to the joint face is not even. 


Bolt and nut design manufacturers recommend a break-in period that allows the tightness of the bolt to relax to a specific level. Micro-embedding of the bolt head and nut to the surface of the joint is what causes this relaxation. Embedding can happen with both hard and soft materials. Embedding on joints with design issues or failure to achieve the specified tension causes a loss in the clamping force. That means the bolt and nut get loose. 

Differences in Thermal Expansion

Sometimes the material of the bolt and the joint are not the same. Thus, temperature changes may not affect them the same way. Cycling industrial processes and environmental changes can lead to significant temperature differences. Therefore, the bolt material may have a rapid contraction and expansion that makes it lose its hold. 


Look out for these causes of loose nuts and bolts and avoid them. That way, the bolts will not lose their clamping force. You can also ensure your bolts remain secure by getting the right ones for your applications. So you should get your pins from a reliable nuts and bolts supplier.

To learn more, contact a nuts and bolts supplier.