Nyloc Nut (Nylon-Insert Lock Nut)
Direct Answer
The Nyloc Nut (Nylon-Insert Lock Nut / Prevailing Torque Nut, standardized under ISO 7040 and DIN 985) incorporates a non-threaded polymer nylon ring permanently captured in an upper crown collar. When threaded onto a bolt, the nylon insert deforms elastically around the bolt threads, generating high frictional prevailing torque that prevents vibrational back-off.
Source: ISO 7040 / ISO 10511 (Thin) / DIN 985 / ASME B18.16.6
Specs
| Standard Specifications | ISO 7040 (Standard height) / ISO 10511 (Low profile) / DIN 985 / ASME B18.16.6 |
| Locking Mechanism | Radial elastic compression of unthreaded polyamide nylon collar |
| Operating Temperature Range | -50°C to +120°C (-58°F to +248°F) |
| Prevailing Torque Behavior | Maintains locking friction even without axial bolt preload (free-spinning torque) |
| Reusability Guidelines | Reusable 2 to 3 times before nylon wear reduces prevailing torque below safety limits |
| Primary Applications | Automotive suspension, aircraft, lawnmowers, go-karts, robotic actuators |
Prevailing Torque Operating Principle
Standard nuts lose all holding power the moment clamping tension drops slightly. As a bolt enters a Nyloc nut, the screw threads force their way through the smaller-diameter nylon ring, compressing the nylon. This generates continuous radial friction (prevailing torque) against the thread flanks, ensuring the nut cannot vibrate off even if the bolted joint is completely loose.
Temperature and Reusability Constraints
- High Heat Limit: Because standard nylon begins softening above 120°C (248°F), Nyloc nuts cannot be used on engine exhaust manifolds or brake caliper brackets (where all-metal distorted-thread lock nuts like DIN 980 are required).
- Reusability: Each threading cycle permanently cuts micro-grooves into the nylon. While safe for 2–3 removals, critical aviation and racing regulations mandate replacing Nyloc nuts with brand-new units after every disassembly.