Our DIN 982 metric nylon insert heavy duty locknuts use a nylon collar that deforms around the bolt thread to create a friction lock that resists loosening under vibration and shock. Taller than standard nyloc nuts, these heavy duty variants provide increased prevailing torque for demanding structural and industrial applications.

Nylon Insert Heavy Duty Locknuts — Metric Sizes

What Are Nylon Insert Heavy Duty Locknuts?

Nylon insert heavy duty locknuts — commonly called heavy duty nyloc nuts — are prevailing torque locknuts that incorporate a nylon ring insert at the top of the nut. When the bolt passes through the nut and into the nylon collar, the collar deforms around the bolt thread, creating a friction-based resistance to rotation. This locking action is maintained throughout the life of the fastener and does not require any additional tools or locking compounds.

The heavy duty designation refers to a taller nut body compared to standard DIN 985 nyloc nuts, providing a longer thread engagement and higher prevailing torque values — essential for applications subject to severe vibration, shock loading, or dynamic forces.

Key Features and Benefits

•        Nylon Insert Lock: Deformable nylon collar creates a reliable friction lock on the bolt thread without tools or adhesives.

•        Heavy Duty Height: Taller body than standard nyloc (DIN 985) provides greater thread engagement and higher prevailing torque.

•        Vibration Resistance: Maintains clamp load under continuous vibration without re-torquing.

•        Re-usable (Limited Cycles): Can be removed and reinstalled, though locking torque decreases with repeated use.

•        Wide Temperature Range: Suitable for operating temperatures up to 120°C (standard nylon insert).

Materials and Finishes

•        Carbon Steel — Zinc Plated (Grade 8): Standard industrial and structural applications.

•        Stainless Steel (A2 / A4): For corrosion-critical environments with nylon or all-metal insert options.

•        Hot-Dip Galvanized: For outdoor structural applications requiring maximum corrosion protection.

Standards Compliance

•        DIN 982 — Hexagon locknuts, heavy type, with nylon insert

•        ISO 7042 — All-metal prevailing torque hexagon nuts (related standard)

•        ISO 2320 — Mechanical properties and test methods for prevailing torque locknuts

Size Range and Availability

Available in M4 through M24, with hex widths conforming to DIN 982 specifications.

Frequently Asked Questions (FAQs)

1. What is the difference between DIN 982 and DIN 985 nylon insert locknuts?

DIN 982 is the heavy duty (high type) locknut with a taller body, providing greater thread engagement and higher prevailing torque. DIN 985 is the standard type with a lower profile, suitable for lighter-duty applications.

2. How many times can a nylon insert locknut be reused?

Most standards allow for up to five reuse cycles, though prevailing torque diminishes with each. For safety-critical applications, single use is recommended.

3. What is the maximum temperature for a standard nylon insert locknut?

Standard nylon (PA6) inserts are rated to approximately 120°C. For higher temperatures, all-metal prevailing torque nuts are recommended.

4. Are nylon insert locknuts suitable for outdoor use?

Zinc-plated carbon steel provides moderate outdoor corrosion resistance. For prolonged outdoor or marine exposure, stainless steel or hot-dip galvanized variants are recommended.

5. Do nylon insert locknuts require a torque wrench?

A torque wrench is recommended for critical applications to achieve correct clamp load without over-tightening, which can damage the nylon insert.

6. Can nylon insert locknuts be used with stainless bolts?

Yes — stainless steel locknuts are specifically designed for pairing with stainless bolts to prevent galvanic corrosion in the assembly.

7. What is prevailing torque?

Prevailing torque is the rotational resistance of a locknut independent of clamp load — it is the torque required to run the nut along the bolt thread before and after seating, and is what provides the locking action.

8. Are these nuts suitable for structural bolting?

Heavy duty nyloc nuts are used in structural assemblies, but for primary structural bolting, refer to the relevant structural bolting standard and specify the appropriate property class.

9. What wrench size is needed for an M10 DIN 982 locknut?

An M10 DIN 982 heavy duty locknut uses a 17mm wrench across flats.

10. Can I use a nylon insert locknut with a fine thread bolt?

Yes — nylon insert locknuts are available in fine thread pitches for applications requiring fine thread engagement, such as precision machinery or thin-walled assemblies.