Hex Flange Nuts
Manufacturer
India · Mumbai
Anatomy of a Hex Flange Nut — A Washer Built Into the Nut
A hex flange nut is a standard hex nut with a wide, integral circular flange forged or formed directly onto its bearing face — significantly wider in diameter than the hex body itself, and considerably wider than the bearing face of a plain hex nut at the same thread size. This flange does the job a separate flat washer would otherwise be added to perform: spreading the nut’s clamping load over a much larger contact area of the mating surface, reducing the local bearing pressure and the risk of the nut digging into or deforming a softer material beneath it.
Many hex flange nuts additionally have a series of small radial serrations machined or formed into the underside of the flange. As the nut is torqued down, these serrations bite slightly into the mating surface, providing genuine resistance to back-rotation from vibration — a real, mechanical anti-vibration function achieved through the flange geometry itself, not a separate spring, insert, or distorted thread feature.
The practical result is a single component doing the work of two — a standard hex nut normally needs a separate flat washer added underneath it to spread load and protect a softer mating surface; a flange nut builds that washer function directly into the part, and the serrated variant adds a genuine vibration-resistance benefit on top, all without any additional assembly step or loose component to keep track of.
Why Hex Flange Nuts — One Part, Fewer Assembly Steps
Eliminates a Separate Loose Washer
One less component to stock, pick, and place during assembly — a genuine benefit on high-volume production lines where every eliminated loose part reduces assembly time and the risk of a washer being missed entirely.
Wider Bearing Area Protects Softer Materials
The flange’s larger diameter spreads clamping load over significantly more contact area than the hex body alone would provide, reducing the risk of the nut digging into or deforming sheet metal, plastic, or other softer mating surfaces.
Genuine Vibration Resistance on Serrated Variants
The serrated flange face bites into the mating surface as the nut is torqued down, providing real mechanical resistance to back-rotation — a meaningfully different anti-vibration mechanism from friction-based nylon inserts or distorted thread.
Self-Aligning, Consistent Orientation
Because the flange is integral to the nut rather than a separate washer that could be installed off-centre or omitted, every flange nut installation delivers exactly the same bearing geometry and serration engagement, run after run.
Two Functions, One Part — The Core Value Proposition
Consider the conventional alternative: a plain hex nut, paired with a separate flat washer beneath it, to spread bearing load and protect the mating surface. That’s two components, two items to stock, and two things that must both be present and correctly oriented for the joint to perform as intended — a washer can be forgotten, installed upside down, or simply not stocked in the right size at the point of assembly.
A hex flange nut with a serrated face replaces that two-part assembly with a single component that does everything the nut-plus-washer pair did, and adds a genuine anti-vibration function neither the plain nut nor the plain washer provided on their own. This is the core reason flange nuts are so heavily specified in high-volume automotive and appliance assembly — fewer parts to manage, fewer assembly errors possible, and a locking benefit obtained essentially for free within the part’s own geometry.
This same integral-flange principle is the foundation for every flange nut variant in our range — our 12-point flange nut keeps this exact washer-and-serration function while additionally changing the external drive geometry to a double-hex form, specifically to reduce the wrench swing arc needed in confined-clearance applications. Where that additional swing-arc benefit isn’t required, the standard hex flange nut described on this page remains the simpler, more universally tool-compatible default.
Serrated vs Non-Serrated (Plain) Flange Nuts
Both eliminate the separate washer — the difference is whether the flange bites into the surface beneath it.
Serrated Flange Nut
Small radial teeth on the flange underside bite into the mating surface as the nut is torqued, providing genuine anti-vibration resistance — the standard choice wherever back-rotation under vibration is a real concern.
Non-Serrated (Plain) Flange Nut
A smooth flange underside still eliminates the separate washer and spreads bearing load, but without biting into or marring a painted, plated, or otherwise finished mating surface.
Hex Flange Nut Material & Strength Options
Standard property class convention applies — the flange geometry performs identically across all grades.
Hex Flange Nut Configurations
Serrated and non-serrated flange nuts across the full material range. M5–M20.
Serrated Hex Flange Nut
Standard serrated flange configuration per DIN 6923. M5–M20. The default specification for automotive and machinery vibration-prone assemblies.
Non-Serrated Hex Flange Nut
Smooth flange face per ISO 4161. M5–M20. For painted, coated, or finished mating surfaces where serration marring is undesirable.
12-Point Flange Nut
Same serrated integral flange, with double-hex drive halving the required wrench swing arc for confined-clearance access. View 12-Point Flange Nuts →
Custom Hex Flange Nuts
Non-standard flange diameter, custom serration patterns, and drawing-specific configurations. Contact sales@akbarfasteners.in with thread size, flange type, and grade requirement.
Hex Flange Nut Size Chart — M5 to M20
Across-flats dimension and flange diameter for each thread size — flange diameter is significantly larger than the hex across-flats, unlike a plain hex nut.
| Thread Size | Across Flats (mm) | Flange Diameter (mm) | Height (mm) |
|---|---|---|---|
| M5 | 8.0 | 11.8 | 5.0 |
| M6 | 10.0 | 14.2 | 6.0 |
| M8 | 13.0 | 17.9 | 8.0 |
| M10 | 15.0 | 21.8 | 10.0 |
| M12 | 18.0 | 26.0 | 12.2 |
| M14 | 21.0 | 29.9 | 14.2 |
| M16 | 24.0 | 34.5 | 16.2 |
| M20 | 30.0 | 42.8 | 20.2 |
Flange diameter is meaningfully larger than the hex across-flats at every size — this additional bearing area is the entire reason a separate washer becomes unnecessary.
Hex Flange Nuts Application Areas
High-volume assembly wherever eliminating a separate washer and adding vibration resistance both matter.
Automotive Assembly
high-volume production lines
Vibrating Machinery
agricultural equipment
Appliance Manufacturing
reduced part-count assembly
General Machine Building
reduced loose-part handling
Rail & Heavy Transport
vibration-resistant assembly
HVAC Equipment
sheet-metal casing fastening
Solar & Structural Mounting
vibration-resistant outdoor duty
Marine Equipment
engine room hardware
Hex Flange Nut Standards Coverage
Same ISO 9001:2015 quality system as our complete fastener range. Flange diameter and serration pattern verified against DIN 6923 on every production lot.
Complete Documentation Package
Grade / Standard Stated
Proof Load · Hardness
Flange Ø · Serration
Conformance
On Request
Related Nut Types & Materials
Hex flange nuts for washer elimination and general vibration resistance. 12-point flange nuts for confined-space wrench access. Standard hex nuts for the baseline without a flange.
12-Point Flange Nuts
The confined-space access variant of this same flange principle — identical washer and serration function, with a double-hex drive for reduced wrench swing arc.
View 12-Point Flange Nuts →Standard Hex Nuts
The plain, no-flange baseline this product builds on — correct wherever a separate washer and anti-vibration bite are not required.
View Standard Hex Nuts →Full Nut Range
Complete nut manufacturing capability at Akbar Fasteners — hex, heavy hex, flange, K-Lock, and all specialty forms across carbon steel through exotic alloy.
View Nut Range →SS 316L Fasteners
For hex flange nut applications in marine, coastal, or wash-down environments where carbon steel’s corrosion resistance is insufficient.
View SS 316L →Need Hex Flange
Nuts?
Serrated or plain · thread size · grade · quantity. Akbar Fasteners Pvt. Ltd. responds within 24 hours.
Export: +91 8696 32 4646 · Support: +91 800 9315 333 · export@akbarfasteners.in