Nylon (Nyloc) Insert Nuts

A nylon insert nut - universally known as a Nyloc nut - is the self-locking nut that uses a deformable nylon insert to grip the bolt thread and resist loosening under vibration, cyclic loading, and thermal cycling. At the DIY Hardware Store, our nylon insert nuts are available in the metric sizes used across automotive, engineering, machinery, and general assembly applications where nut retention is required without secondary locking devices.

The nylon insert sits in the top of the nut above the metal thread. When the bolt passes through the metal thread and encounters the nylon insert, it deforms the nylon slightly to cut a mating thread - this interference creates a significant prevailing torque that prevents the nut from rotating backwards on the bolt under vibration. The nut can be removed with a spanner, but will not loosen spontaneously in service.

Nyloc nuts are single-use in theory - the nylon insert compresses permanently on first installation - but in practice they can often be reused a limited number of times if undamaged. Available in zinc-plated steel in metric sizes at the DIY Hardware Store, sold as singles and in packs.

  • Nylon insert provides self-locking prevailing torque
  • Resists loosening under vibration and cyclic loading
  • No secondary locking device required
  • Removable with spanner - not permanently deformed
  • Metric sizes in zinc-plated steel
  • Standard for automotive, machinery, and engineering assembly