All You Wanted to Know about Metric Nyloc Nuts

A metric nyloc nut, which is also known as polymer insert lock nut, nylon insert lock nut or elastic stop nut, is a kind of fastener, which combines a nylon component and a nylon collar insert to efficiently padlock the rivet into accurate position on the bolt.

Metric nyloc Nuts



The insert is positioned at the end of the nut and its inner diameter is bit smaller than the entire diameter of the screw. The polymer insert spreads elastically over the threads of the screw without cutting the threads into the nylon. Moreover, it clamps the nut in two ways. Firstly, it pushes the end part of the screw threads against the head of the nut threads, thereby enhancing the friction between the two. Secondly, the nylon component employs a compact force against the rivet itself.



The nylon component of the nyloc nut has a smaller inside diameter than the actual nut, thereby locking the fastener in place by gripping the nylon firmly around the bolt when fastened. Unlike a common locking washer, this particular metal piece stops the nut from loosening due to vibration, as the nylon is firmly wedged into the threads, thereby offering enough resistance to movement.

X section of a Lock Nut Bolt joint



One common issue associated with common nuts and bolts is that they can get loose over time due to the effect of the vibration. Therefore, you can go for chemical thread-locking melanges, which help in lessening the development of loosening these metal objects. However, this process is quite time-consuming and in case of difficult-to-reach areas, it’s nearly impossible to acquire desired results.

The metric nyloc nut on the other hand, enables a bolt to be fastened conveniently without fear of getting loose under any condition. Also, you won’t face any problem in employing this nut than a conventional non-locking nut.

However, always remember that these nuts cannot be threaded tightly only by using your fingers. Instead, you’ll require a suitable wrench to tightly secure them.


Did you know?

The metric nyloc nuts can maintain their locking ability even at 250°F (121 °C) and that ‘Nyloc’ is a registered trade name of Forest Fasteners.

In Australia it is a registered trade mark of Exafast Pty Ltd.


Bulk no of Metric Nylon nuts


Advanced Features

In the market, these nuts are sold at a bit higher price as compared to a standard nut. This higher range had once become a concern, as these locking rivets were used as a one-time use supply i.e. once such rivets were used on bolts then they had to be discarded and new pieces were used whenever the fastener was removed.

In order to overcome such issues, these nuts were then highly advanced in terms of nylon formula. Today, modern nylon-type locking nuts can be conveniently reused several times without any risk of failure, thereby enabling these fasteners a feasible option even in most critical fastening areas.


Things to keep in mind 

Although these round objects can be reused in several applications still it’s recommended to go for fresh nuts, especially in case of critical fastener connections. Even the slightest risk of failure can slap manufacturer with a ban with the usage of old locked nuts in all critical applications, including rod bolts, cylinder head bolts and bearing cap bolts. The advanced nylon formulas easily enable the nyloc nuts to be applied in various internal engine applications without concern.


Useful Tip

The World Wide Web is always a great medium to look for some potential metric bolt and nut providers. You can read testimonials online and can also search via local listings such as Google Places, Yahoo Local, Yelp etc. as these is a huge repository of reliable web stores, such as Mutual Screw on the net.