Hex Flange Nut (Serrated & Non-Serrated)
Our DIN 6923 metric hex flange nuts integrate a wide bearing flange directly into the nut, replacing the need for a separate washer. Available in serrated and non-serrated variants, they offer exceptional vibration resistance and load distribution for automotive, structural, and industrial assembly.
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Hex Flange Nuts — Serrated and Non-Serrated Metric Sizes
What Are Hex Flange Nuts?
Hex flange nuts are hexagonal nuts with an integrated circular flange on the bearing face. This flange acts as a built-in washer, spreading the clamping load over a larger contact area and eliminating the need for a separate flat washer in most applications.
Serrated hex flange nuts feature radial serrations machined into the flange underside. These serrations bite into the mating surface when tightened, creating a mechanical lock that resists loosening under vibration — making them a preferred choice in automotive underbody, powertrain, and suspension assemblies. Non-serrated flange nuts provide the same wide bearing surface without serrations, suitable for applications where surface marking must be avoided.
Key Features and Benefits
• Integrated Flange Washer: Eliminates the need for a separate washer, reducing parts count and assembly time.
• Serrated Option: Radial serrations provide vibration-resistant locking without additional locking elements.
• Wide Bearing Surface: Distributes clamping load to prevent pull-through in thin or soft substrates.
• Standard Hex Profile: Compatible with standard open-end, box, and socket wrenches.
• Automotive-Grade Availability: Zinc plated and geomet coated options meet automotive corrosion specifications.
Materials and Finishes
• Carbon Steel — Zinc Plated (Grade 8): General-purpose, moderate corrosion resistance.
• Carbon Steel — Geomet / Dacromet Coated: High corrosion resistance for underbody automotive use.
• Stainless Steel (A2 / A4): For marine, chemical, and food-grade applications.
Standards Compliance
• DIN 6923 — Hexagon flange nuts
• ISO 4161 — Hexagon nuts with flange
• DIN 6927 — Hexagon flange nuts with serration (prevailing torque type)
Size Range and Availability
Available in M5 through M20.
Frequently Asked Questions (FAQs)
1. What is the difference between a serrated and non-serrated hex flange nut?
Serrated flange nuts have radial teeth on the flange underside that bite into the mating surface, providing vibration-resistant locking. Non-serrated nuts provide the same wide bearing surface without marking the substrate.
2. Do hex flange nuts replace washers?
In most applications, yes — the integrated flange performs the same load-distribution function as a flat washer, reducing parts count and assembly cost.
3. Are serrated flange nuts reusable?
They can be reused, but locking effectiveness diminishes as the serrations flatten with repeated installation. For critical applications, replacement is recommended.
4. What wrench size does an M8 hex flange nut require?
An M8 DIN 6923 hex flange nut requires a 13mm wrench across flats.
5. Are hex flange nuts suitable for automotive applications?
Yes — they are extensively used in automotive manufacturing for body panels, brackets, and underbody components, particularly in geomet or zinc-plated steel.
6. Can serrated flange nuts be used on painted surfaces?
The serrations will mark painted or soft surfaces. If surface marking is unacceptable, use non-serrated flange nuts with a separate locking element.
7. What is the property class of your carbon steel flange nuts?
Our standard carbon steel hex flange nuts are Grade 8, with proof load stress of 800 MPa.
8. What coating is best for outdoor or underbody use?
Geomet or Dacromet coating provides the highest corrosion resistance for outdoor and underbody applications, outperforming standard zinc plating.
9. Are stainless steel serrated flange nuts available?
Yes — A2 stainless serrated flange nuts are available. Note that A2 stainless is slightly softer than carbon steel, so serrations may not bite as aggressively into hardened substrates.
10. What is the DIN standard for hex flange nuts with serration?
DIN 6927 covers hexagon flange nuts with serrations that also act as prevailing torque elements. DIN 6923 covers standard hex flange nuts without prevailing torque.
