Nylon Lock Nut

Material: SS Steel, Carbon Steel etc.

Surface Finish: Zinc, Polish, Black etc.

Application: Machine, Bicycle, Telecom, Construction etc.

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Nylon Lock Nut——Nyloc nut

A nyloc nut, also referred to as a nylon-insert lock nut, polymer-insert lock nut, or elastic stop nut, is a kind of locknut with a nylon collar insert that resists turning.

The plastic insert is placed at the end of the nut, with an inner diameter (ID) slightly smaller than the major diameter of the screw. The insert deforms elastically over the threads of the screw, without having threads in turn cut into it. The nylon insert locks the nut by friction against the screw under the applied radial compressive force. Nyloc nuts retain their locking ability up to 250 °F (121 °C).


Authorities disagree on whether nyloc nuts should be reused. For example, Carroll Smith (Carroll Smith's Nuts, Bolts, Fasteners, and Plumbing Handbook) notes that the nylon insert is not damaged by installation and therefore they can be reused many times, and a Federal Aviation Administration Advisory Circular allows nuts to be reused if the prevailing torque is within specification. However, an Air Force Technical Order requires replacement of self-locking nuts in critical areas.Various specifications for aerospace-grade self-locking nuts require that the running torque be maintained after a number of cycles of assembly, but without preloading the fastener.

How to Use a Nylon Lock Nut

Nylon lock nuts differ from a standard hex nut in that they have a nylon insert secured within the nut. The nylon insert is located in a tapered section located at the back of the nut. When you install the nylon lock nut onto a bolt or threaded stud, the nylon insert wraps around the threads and locks the nut in place. This gives a nylon lock nut a distinct advantage over a lock washer when the bolt or threaded stud is subject to vibration, as the nylon lock nut is unaffected by vibration.

Step 1

Examine the nylon insert of the nylon lock nut to ensure that the insert is not damaged.

Step 2

Thread the nylon lock nut onto the bolt or threaded stud and turn the nut clockwise with your hand until it no longer turns. This will be the point that the nylon insert contacts the top thread of the fastener.

Step 3

Place the socket that matches the nylon lock nut onto the 3/8-inch drive ratchet.

Step 4

Slide the socket onto the nylon lock nut and turn the handle of the ratchet clockwise to turn the nylon lock nut onto the fastener. You will feel some resistance from the nylon lock nut as you turn it onto the fastener. This is created by the nylon insert and is completely normal.

Step 5

Continue turning the ratchet handle until the nylon lock nut seats tightly against the surface of the material you are securing with the nut.

Step 6

Inspect the nylon insert of the lock nut to ensure that it is intact after installation.