Carbon Steel Lock Nut — Factory Direct Supplier | Huaxia-Steel
Carbon steel lock nuts are engineered fasteners that resist loosening under vibration, thermal cycling, and dynamic loads. Unlike standard hex nuts, lock nuts incorporate a locking mechanism — nylon insert, all-metal prevailing torque, or deformed thread — that creates friction between the nut and bolt threads. Huaxia-Steel supplies nylon insert lock nuts (DIN 985), all-metal lock nuts (DIN 980), and heavy-duty structural lock nuts to ASTM A563, with zinc plating and hot-dip galvanizing for corrosion protection.
Product Overview
Lock nuts are essential in applications where vibration or cyclic loading could cause standard nuts to back off. The most common type, the nylon insert lock nut ( prevailing torque nut ), contains a nylon collar that grips the bolt threads as the nut is tightened, creating consistent friction that resists loosening. All-metal lock nuts use a deformed thread section or a metal insert for high-temperature applications where nylon would degrade. For structural bolting, direct-tension-indicating (DTI) lock nuts ensure proper pre-tension in critical connections.
Specification
Value
Specification Table: Dimensions & Weight
Nylon Insert Lock Nut — DIN 985
| Nominal Size | Width Across Flats (mm) | Height (m, mm) | Thread Pitch (mm) | Weight (g/pc) |
|---|---|---|---|---|
| M6 | 10.0 | 6.0 | 1.0 | 2.6 |
| M8 | 13.0 | 8.0 | 1.25 | 5.8 |
| M10 | 16.0 | 10.0 | 1.5 | 11.0 |
| M12 | 18.0 | 12.0 | 1.75 | 16.5 |
| M16 | 24.0 | 16.0 | 2.0 | 36.0 |
| M20 | 30.0 | 20.0 | 2.5 | 66.0 |
| M24 | 36.0 | 24.0 | 3.0 | 118.0 |
| M30 | 46.0 | 30.0 | 3.5 | 234.0 |
| M36 | 55.0 | 36.0 | 4.0 | 390.0 |
| M42 | 65.0 | 42.0 | 4.5 | 615.0 |
All-Metal Lock Nut — DIN 980 (Top Lock)
| Nominal Size | Width Across Flats (mm) | Height (mm) | Prevailing Torque 1st (Nm) | Prevailing Torque 5th (Nm) |
|---|---|---|---|---|
| M6 | 10.0 | 6.0 | 0.8-3.0 | 0.4-1.6 |
| M8 | 13.0 | 8.0 | 1.5-6.0 | 0.8-3.2 |
| M10 | 16.0 | 10.0 | 2.5-10.0 | 1.3-5.3 |
| M12 | 18.0 | 12.0 | 3.5-14.0 | 1.8-7.5 |
| M16 | 24.0 | 16.0 | 6.5-26.0 | 3.3-14.0 |
| M20 | 30.0 | 20.0 | 10.0-40.0 | 5.0-21.0 |
| M24 | 36.0 | 24.0 | 14.0-56.0 | 7.0-30.0 |
Prevailing torque per ISO 2320. The 5th-assembly torque (after 4 prior assemblies) demonstrates the reusability of the lock nut.
Available Grades
| Grade | Material | Proof Load (MPa) | Hardness (HRC) | Application |
|---|---|---|---|---|
| Grade 5 | Q235 / mild steel | 510 | 22-32 | General purpose, low vibration |
| Grade 8 | 1045 (quenched & tempered) | 827 | 28-34 | High-strength machinery, automotive |
| Grade 10 | 35CrMo (alloy steel) | 1040 | 32-38 | Heavy equipment, structural bolting |
| ASTM A563 Grade DH | Medium carbon, Q&T | 1040 | 27-38 | Structural bolting (A325/A490 bolts) |
Manufacturing Standards
- DIN 985: Hexagon nylon insert lock nuts (standard, most common in Europe/Asia)
- DIN 980: All-metal prevailing torque lock nuts (top lock type)
- ASTM A563: Carbon and alloy steel nuts (Grades A, C, DH, DH3 for structural)
- ISO 2320: Prevailing torque test specification for lock nuts
- ASTM F594: Stainless steel nuts (when SS variant needed)
- JIS B 1180: Hexagon nuts with nylon insert (Japanese standard)
Applications
| Industry | Application | Recommended Type | Surface Treatment |
|---|---|---|---|
| Automotive | Wheel hubs, engine mounts, suspension | Grade 8 nylon insert | Zinc plated |
| Construction | Structural steel connections | ASTM A563 DH | HDG |
| Railway | Track fastening, rail clips | Grade 10 all-metal | Dacromet |
| Petrochemical | Flange bolting (high temp) | All-metal (Grade 8+) | Zinc yellow |
| Wind energy | Tower flange connections | Grade 10 all-metal | HDG |
| Heavy machinery | Excavators, cranes, mining equipment | Grade 10 all-metal | Zinc plated |
Quality Assurance
- Material certification: EN 10204 3.1 MTC with full chemistry and mechanical properties
- Hardness testing: HRC tested per ISO 898-2 (5 pieces per batch minimum)
- Prevailing torque test: per ISO 2320, 1st and 5th assembly torque measured and recorded
- Thread gauging: 6H GO/NO-GO thread gauges, 100% inline inspection
- Coating thickness: XRF measurement, salt spray test per ASTM B117
- Nylon insert verification: visual and dimensional check of nylon ring seat depth
- Third-party inspection: SGS, BV, TUV available on request
Packaging & Shipping
| Package Type | Quantity | Weight (kg) | Notes |
|---|---|---|---|
| Plastic bag | 50-500 pcs | 0.5-5 | Small sizes M3-M12 |
| Carton box | 500-2000 pcs | 5-25 | Medium sizes M10-M24 |
| Wooden case | 100-500 pcs | 15-50 | Large sizes M24-M48 |
| Pallet | Multiple cartons | 500-1000 | Bulk orders |
All export packaging includes VCI anti-corrosion paper, desiccant packs, and ISPM-15 compliant wooden pallets. Custom labeling with part numbers, batch numbers, and QR codes available.
Conclusion
Carbon steel lock nuts are critical safety components that prevent bolt loosening in dynamic and vibrating environments. Choosing the right type (nylon insert vs all-metal), grade (5/8/10), and surface treatment ensures long-term joint integrity. Huaxia-Steel supplies lock nuts from M3 to M48, with full ISO 2320 prevailing torque certification and global shipping capabilities.
Need carbon steel lock nuts for your project? Contact Huaxia-Steel for factory-direct pricing, full MTC, and global shipping.
