The Hex Flange Nut (commonly known as a serrated flange nut, collar nut, washer-head nut, or DIN 6923 / ISO 4161 fastener) is an integrated one-piece fastener combining a standard hexagonal nut body with a wide circular integrated washer base. Designed to eliminate the need for a separate flat washer, the flange face distributes clamping pressure over a larger surface area to span oversized or slotted mounting holes. Available with directional locking serrations that bite into joint material to resist severe vibration, our hex flange nuts are manufactured in carbon steel (Property Classes 4, 8, and 10) and austenitic stainless steel (SS304/A2-70 and SS316/A4-80) in strict compliance with global ISO standards.
Technical Specifications of Hex Flange Nuts
We supply both serrated face (self-locking ratcheting action) and smooth face flange nuts across various strength grades and corrosion-resistant coatings. Over-tapped thread options are available for hot-dip galvanized nuts to fit heavy zinc coatings on outdoor structural bolts.
| Property Class / Grade | Raw Material Base | Proof Stress Rating | Bearing Face Design | Available Surface Treatments |
|---|---|---|---|---|
| Class 4 / Class 6 | Low Carbon Steel (Q195 / Q235B) | 400 – 600 N/mm² | Serrated Anti-Slip / Smooth Plain | Electro-Zinc Plated (Blue-White / Yellow) |
| Class 8 (High Tensile) | Medium Carbon Steel (45# Quenched) | 800 N/mm² | Serrated Anti-Slip / Smooth Plain | Black Oxide, Electro-Zinc, Hot-Dip Galvanized (HDG) |
| Class 10 (Extra High Tensile) | Quenched & Tempered Alloy (40Cr) | 1000 N/mm² | Serrated Anti-Slip / Smooth Plain | Black Oxide, Electro-Zinc, Dacromet, HDG |
| Stainless A2-70 / A2-80 | Austenitic Stainless Steel SS304 (1.4301) | 700 – 800 N/mm² | Serrated Anti-Slip / Smooth Plain | Passivated Clean Natural / Electropolished |
| Stainless A4-70 / A4-80 | Austenitic Stainless Steel SS316 (1.4401) | 700 – 800 N/mm² | Serrated Anti-Slip / Smooth Plain | Passivated Clean Natural / Electropolished |
Multi-Station Cold Heading and Flange Stamping Process
At our manufacturing plant in Handan, China, hex flange nuts undergo precision cold forming, automated thread tapping, heat treatment, and surface plating:
- Multi-Station Cold Forming: High-speed automated former machinery punches raw wire rod into hex geometry while expanding the integrated wide flange washer base in a single continuous die stroke.
- Precision Serration Stamping: Directional anti-rotation teeth are stamped under heavy die pressure onto the flange bearing face, providing high breakaway torque resistance against back-off.
- High-Precision Internal Tapping: Tapping units cut metric 6H internal threads (or over-tapped 6AZ threads for HDG nuts) to guarantee low driving friction and smooth assembly.
- Surface Coating & Chemical Passivation: Electro-zinc plating (5–12 µm), Hot-Dip Galvanizing (45–85 µm molten zinc immersion), or acid passivation for stainless steel items.
Versatile Industrial Applications of Hex Flange Nuts
Due to their vibration resistance and wide load-bearing flange surface, hex flange nuts serve as key structural fasteners worldwide:
- Solar PV Racking & Mounting Systems: SS304 / SS316 serrated flange nuts securing aluminum solar panel rails and ground mount framing.
- Automotive Chassis & Engine Frames: Fastening vehicle exhaust systems, suspension control arms, and frame brackets subjected to severe road vibration.
- Structural Steel Framing & Cable Tray Systems: Fastening strut channels, electrical cable tray brackets, and HVAC ductwork without requiring separate washers.
Quality Assurance and Export Packaging for Hex Flange Nuts
Handan YiHao Fastener enforces strict Quality Assurance (QA) standards for all overseas export orders. Testing procedures include 100% thread plug gauge go/no-go checks, flange diameter and thickness gauge measurement, proof load testing, and salt spray validation.
All export orders are bulk packed in heavy-duty 25kg inner cartons, neatly stacked on ISPM 15 compliant fumigated wooden pallets, and wrapped in protective stretch film for safe maritime freight.
Request Factory Direct Pricing for Hex Flange Nuts
Looking for a trusted manufacturer in Handan, China for carbon steel or stainless steel hex flange nuts (Class 4, Class 8, Class 10, A2-70, A4-80, DIN 6923 / ISO 4161)? Contact Handan YiHao Fastener today for technical datasheets, serrated vs smooth options, sample shipments, and direct bulk export quotes.
