Hex Flange Nuts
A metric hex nut with an integral circular flange that distributes the clamping load over a wider bearing surface. Available with serrations (DIN 6923) for vibration resistance or without serrations (ISO 4161 style) for smooth bearing surface applications. In Grade 8, Grade 10.9 high-tensile and SS 304 / SS 316 stainless steel.
What is a Hex Flange Nut?
A hex flange nut is a standard hexagonal nut with a wide circular flange forged integrally at the bearing face. The 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 many assemblies. Manufactured to DIN 6923 / ISO 4161, flange nuts are available with serrations on the flange underside for mechanical vibration locking (DIN 6923) or with a smooth bearing surface for coated, thin-sheet or soft substrate applications (ISO 4161 style). Thread tolerance class 6H ensures full compatibility with standard metric bolts and studs.
Standards & Specifications
Hex flange nuts are manufactured and tested to international standards covering dimensional tolerances, mechanical properties and thread form:
- DIN 6923 — Hexagon flange nuts with serrated bearing surface. Specifies flange outer diameter (dc), nut height (k), across-flat dimension (s) and serration geometry for each metric size. Serrations provide mechanical anti-loosening action under vibration.
- ISO 4161 — Hexagon flange nuts, non-serrated. Equivalent flange geometry to DIN 6923 but with a smooth, flat bearing surface. Preferred where serrations would damage surface coatings or where the substrate is too thin to withstand point loading from serrations.
- Thread tolerance 6H — Standard internal thread fit per ISO 965. Compatible with all metric 6g bolts and studs in the same size range.
- Serration variants — With serration (DIN 6923): radial or crossed serrations on the flange underside bite into the mating surface on tightening, preventing rotation under vibration. Without serration (ISO 4161 style): smooth flange for use on painted panels, thin sheet metal or aluminium to prevent surface damage.
Technical Drawing &
Dimensional Tolerances
| Size | Pitch (mm) | A/F — s (mm) | e min (mm) | Height — k (mm) | Flange dia — dc (mm) | ||||
|---|---|---|---|---|---|---|---|---|---|
| nom | min | max | min | max | min | max | |||
| M5 | 0.80 | 8 | 7.78 | 8.00 | 8.79 | 4.7 | 5.3 | 11.8 | 13.2 |
| M6 | 1.00 | 10 | 9.78 | 10.00 | 11.05 | 5.4 | 6.1 | 14.2 | 15.8 |
| M8 | 1.25 | 13 | 12.73 | 13.00 | 14.38 | 6.9 | 7.6 | 17.9 | 19.6 |
| M10 | 1.50 | 15 | 14.73 | 15.00 | 16.64 | 8.6 | 9.4 | 21.8 | 23.8 |
| M12 | 1.75 | 18 | 17.73 | 18.00 | 20.03 | 10.4 | 11.4 | 26.0 | 28.4 |
| M14 | 2.00 | 21 | 20.67 | 21.00 | 23.36 | 11.9 | 12.9 | 29.9 | 32.5 |
| M16 | 2.00 | 24 | 23.67 | 24.00 | 26.75 | 13.9 | 14.9 | 34.5 | 37.5 |
All dimensions in mm per DIN 6923. s = across flats · e = across corners minimum · k = nut height (hex portion) · dc = flange outer diameter. Thread tolerance class 6H.
Sizes Available
Hex flange nuts are stocked in M5 to M16 across all grades and both serrated and non-serrated variants. All sizes metric coarse pitch per DIN 6923 / ISO 4161.
| Size × Pitch | Grade 8 | Grade 10.9 | SS 304 | SS 316 |
|---|---|---|---|---|
| M5 × 0.8 | ✓ | — | ✓ | ✓ |
| M6 × 1.0 | ✓ | — | ✓ | ✓ |
| M8 × 1.25 | ✓ | ✓ | ✓ | ✓ |
| M10 × 1.5 | ✓ | ✓ | ✓ | ✓ |
| M12 × 1.75 | ✓ | ✓ | ✓ | ✓ |
| M14 × 2.0 | ✓ | ✓ | ✓ | ✓ |
| M16 × 2.0 | ✓ | ✓ | ✓ | ✓ |
Applications
Hex flange nuts are specified wherever the assembly benefits from a larger bearing area without a separate washer, or where vibration locking is required without supplementary locking hardware. The integral flange reduces part count and assembly time in high-volume production.