Hex Flange Nut, Serrated
Our serrated hex flange nuts combine a hexagon nut and washer into one fastener, with locking serrations machined into the underside of the flange. The serrations bite into the mating surface to resist vibration loosening, making these DIN 6923 nuts the fast, one-piece choice for automotive, machinery, and sheet-metal assembly.
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Hex Flange Nut Serrated — Metric Sizes
What Is a Serrated Hex Flange Nut?
A serrated hex flange nut is a hexagon nut with an integral wide flange at its base and radial serrations (teeth) on the flange’s bearing surface. The flange spreads the clamping load like a built-in washer, while the serrations dig into the mating surface as the nut is tightened, creating a ratchet effect that resists loosening under vibration. Manufactured to DIN 6923 and EN 1661, serrated flange nuts eliminate separate washers, speed up assembly, and are used extensively in automotive production, agricultural machinery, HVAC ducting, and sheet-metal fabrication.
Key Features and Benefits
- Anti-Vibration Serrations: Radial teeth on the flange face bite into the mating surface, locking the nut against rotation under vibration and dynamic loads.
- Integrated Washer Flange: The wide flange distributes clamping force over a larger area, protecting thin sheet metal and painted surfaces from crushing.
- One-Piece Assembly: Eliminates separate washers, reducing parts count, assembly time, and the risk of missing components on production lines.
- Oversized Hole Coverage: The large flange diameter bridges slotted and oversized holes common in sheet-metal and adjustable bracketry.
- High-Strength Classes: Available in property classes 8 and 10 for structural and driveline bolted joints.
Materials and Finishes
- Carbon Steel Class 8 (Zinc Plated): Standard grade for general machinery and sheet-metal assembly.
- Carbon Steel Class 10 (Zinc Flake): High-strength option with superior corrosion resistance for automotive chassis and suspension joints.
- Stainless Steel (A2 / A4): For food processing equipment, outdoor structures, and corrosive industrial environments.
Standards Compliance
- DIN 6923 — Hexagon nuts with flange (serrated variant)
- EN 1661 / ISO 4161 — Hexagon nuts with flange, metric coarse and fine thread
Size Range and Availability
Available in M5 through M20 in metric coarse thread, with fine thread options on popular automotive sizes.
Frequently Asked Questions (FAQs)
1. What is a serrated hex flange nut used for?
Serrated flange nuts are used wherever vibration resistance and fast assembly matter: automotive chassis and body assembly, agricultural and construction machinery, HVAC ducting, guarding, and sheet-metal fabrication.
2. How do the serrations on a flange nut work?
As the nut is tightened, the radial teeth embed slightly into the mating surface. Any loosening rotation forces the teeth to climb their own impressions, creating resistance that keeps the nut tight under vibration.
3. Do serrated flange nuts need a washer?
No. The integral flange acts as a built-in washer, spreading load over a wide area. Adding a washer would actually defeat the serrations by giving them a loose surface to grip.
4. Will serrated flange nuts damage painted or coated surfaces?
The serrations are designed to bite into the surface, so they will mark paint and coatings. For decorative or sealed surfaces, use a plain (non-serrated) flange nut instead.
5. What is the DIN standard for serrated flange nuts?
Serrated hex flange nuts are manufactured to DIN 6923, with EN 1661 and ISO 4161 covering the equivalent metric flange nut dimensions.
6. Can serrated flange nuts be reused?
They can be reused a limited number of times, but each tightening cycle flattens the serrations and the mating surface impressions, gradually reducing locking performance. Replace them in critical joints.
7. What is the difference between serrated and non-serrated flange nuts?
Both share the same flange geometry, but the serrated version has locking teeth on the bearing face for vibration resistance, while the plain version has a smooth face that will not mar the surface.
8. What sizes of serrated flange nuts do you stock?
We stock M5 through M20 in metric coarse thread, plus fine thread variants on common automotive sizes such as M10 and M12.
9. Are serrated flange nuts suitable for soft materials like aluminium?
Yes — the serrations grip aluminium very effectively. Use stainless steel nuts on aluminium parts to avoid galvanic corrosion, and check that the flange bearing pressure suits thin-wall sections.
10. What torque should I use on a serrated flange nut?
Use the standard torque for the bolt size and property class; the serrations engage at normal seating torque. Because the flange face has higher friction, follow the joint designer’s specified torque where available.
