Nylon Insert Lock Nuts
What are Nylon Insert Lock Nuts?
Nylon insert lock nuts—often called nyloc nuts—are hex nuts with a captive nylon ring pressed into a recess at the top of the nut. As the mating bolt engages the threads, the nylon collar deforms around the bolt’s threads to create prevailing torque that resists loosening from vibration and shock.
How do Nylon Insert Lock Nuts work?
The nylon collar slightly interferes with the bolt’s threads to generate friction. This prevailing torque resists back-off, while the hex body provides standard clamping force. Unlike chemical threadlockers, the locking action is mechanical and clean, and unlike all-metal lock nuts, nyloc nuts lock without galling the threads.
Benefits of Nylon Insert Lock Nuts
- Vibration resistance: prevailing torque helps prevent back-off in dynamic assemblies.
- Reusable (limited cycles): nylon collar maintains lock for several cycles when within temperature and wear limits.
- Non-marring: nylon insert protects male threads compared to some all-metal locking styles.
- Clean & dry: no cure times or adhesives required.
- Versatile: available in stainless steel, zinc-plated steel, brass, aluminum, and metric/imperial sizes.
Common Applications for Nylon Insert Lock Nuts
- Automotive and powersports assemblies
- Industrial machinery and equipment
- HVAC, electrical, and light fabrication
- Furniture, fixtures, racking, and enclosures
- Marine and outdoor projects (use stainless where corrosion resistance is needed)
What materials and finishes are available?
- 18-8 / 304 Stainless Steel: general corrosion resistance for indoor/outdoor use.
- 316 Stainless Steel: enhanced corrosion resistance for marine and salt exposure.
- Zinc-Plated Steel: economical, bright finish for dry, indoor environments.
- Brass & Aluminum: non-magnetic or decorative use cases.
- Metric & Imperial: standard hex patterns in coarse and fine threads.
How do I size and select a Nylon Insert Lock Nut?
- Match the nut to the bolt’s diameter and thread pitch (e.g., 1/4-20, M8-1.25).
- Select the right material for the environment (e.g., 316 stainless for marine).
- Choose strength class/grade to match the bolt specification when required.
- Verify clearance: nyloc nuts are slightly taller—ensure space for the nylon crown.
- Temperature limits: typical nylon inserts are best below ~250°F (121°C). For higher temps, consider all-metal lock nuts.
Installation Tips for Nylon Insert Lock Nuts
- Start threads by hand to avoid cross-threading, then tighten with the appropriate wrench or driver.
- Ensure 2–3 full threads protrude past the nylon ring after tightening so the insert fully engages.
- Avoid lubricants on the nylon insert; they can reduce prevailing torque.
- Don’t overheat during assembly—excess heat can soften the nylon and reduce locking performance.
- For soft materials or oversized holes, use a flat washer to distribute load.
Are Nylon Insert Lock Nuts reusable?
Yes—within limits. The nylon ring wears each time it’s installed and removed. If prevailing torque feels weak or the insert looks damaged, replace the nut. For critical joints or after multiple service cycles, plan on installing a new nyloc nut.
Nylon Insert Lock Nuts — Frequently Asked Questions
Quick answers to common nyloc questions. If your use case isn’t covered, tell us about your environment, loads, and thread size and we’ll recommend an exact spec.
Most are suitable up to about 250°F (121°C). For higher temperatures, use an all-metal prevailing-torque lock nut or a castle nut with cotter pin.
Sometimes, but the insert wears. Replace if the nut spins too easily, the nylon looks damaged, or the joint is safety-critical.
Generally no, the nylon provides prevailing torque. Threadlocker is optional redundancy for extreme vibration.
Use zinc-plated steel for indoor/dry; 18-8 (304) for general outdoor; 316 stainless for marine/chlorides; yellow zinc where appearance or extra coating is desired.
Follow the specified torque for the bolt size/grade and materials. Expect slightly higher run-on torque as the nylon engages the threads.
Nylon is gentler than all-metal prevailing-torque nuts and is less likely to mar coated surfaces. Use washers when finish protection is critical.
The nut’s metal provides corrosion resistance (e.g., stainless or plated steel). The nylon insert itself is not a corrosion barrier.
Match diameter and pitch exactly to the bolt (e.g., 1/4"-20 vs 1/4"-28, M8-1.25 vs M8-1.0) and select a material that suits the environment and load.