nyloc

Nylock nuts, or nylon-insert lock nuts, are a type of locknut that combines a standard hex nut with a molded nylon collar insert. The nylon insert sits in the bore of the nut and is deformed by the bolt threads when the nut is tightened. This deformation creates friction between the insert and the threads, helping to resist loosening caused by vibration, dynamic loads, and thermal cycling.

Construction and variants: A typical nyloc nut uses a steel hex nut with an undersized inner bore and a nylon insert occupying part of the nut’s thickness. The nylon is usually a nylon 6/6 formulation, and the outer body may be zinc-plated steel or stainless steel for corrosion resistance. Nylon inserts can be unfilled or glass-filled to improve stiffness and creep resistance. Nyloc nuts are available in metric and imperial thread sizes and in a range of materials to suit different environments.

Performance and limitations: The locking action provides important vibration resistance but can degrade with repeated reassembly, exposure to high temperatures, solvents, or aggressive cleaning agents. Standard nyloc nuts are typically rated for ambient temperatures up to about 120°C, with high-temperature nylon variants extending that range. They are not ideal for long-term high-load cycling or for use with soft or damaged threads, where the insert may not seat properly.

Applications and use: Nyloc nuts are widely used in automotive, machinery, consumer electronics, and general mechanical assemblies where a reliable, self-contained locking mechanism is desirable and where operating temperatures are within the insert’s range. They are often chosen to avoid separate locking washers or thread-locking liquids.