Trojan Special Fasteners Ltd routinely manufactures nylon insert nuts to customer's requirements in multiple material and finish combinations. Nylon insert nuts are typically hexagon nuts with a polyamide (usually Nylon 66) insert.

The non-metallic ring is placed on one of the nut and as it's inner diameter is slightly smaller than the major diameter of the screw, it elastically deforms over the threads of the screw. This means that the non-metallic ring applies a compressive force against the screw which means that the nut doesn't loosen with vibration and also cushions against vibration as well.

These kind of nuts are also known as aircraft lock nuts, elastic lock nuts, elastic stop nuts, nyloc nuts, nylock nuts and nylon insert stop nuts. These are reusable (up to a limited number of time) because the nylon insert will return to its original shape. Nylon insert nuts are a form of prevailing torque nut because they have a mechanism that creates frictional interference between threads of mating components. This also means that application has to be with a wrench or spanner because the nylon ring creates increased torque.

In addition to standard preferred sizes, we also manufacture non preferred and non standard or special thread and nut forms and sizes.

Typical nuts can be used up until 120 degrees Celsius, but certain materials are available (on request) which can be used in nuts for higher temperatures, although we would recommend an all-metal prevailing torque type nut for high temperature use.

There is some disagreement if nyloc/nylock/nylon insert nuts can or should be reused. Some polymer rings are not damaged upon installation, in which case the fastener is reused multiple times. However, this does not take into account any degradation of the polymer ring which comes about due to the stresses it's under upon application or even removal, how long the fastener has been in use, how many times it has been re-tightened or even what chemicals and pollutants it may have come into contact with. It is common for companies to reuse and retighten fasteners if the prevailing torque is within specified ranges.

However, in critical applications, Trojan always suggests replacement of the fastener. They are relatively inexpensive and easy to replace, so there should not be a reason for retightening or reapplication. 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.