Quick comparison

1. Standard identity and component role

The DIN 6923 product is a hexagon nut with flange. Its flange provides a larger bearing surface, and the product has smooth and serrated bearing-face options. The DIN 6921 product is a hexagon bolt with a circular flange under the head. The flange acts as a built-in washer and increases the bearing area under the bolt head.

These roles are complementary rather than interchangeable. A nut specification cannot be substituted for a bolt specification simply because both include a flange. The purchasing record should therefore identify the component type, standard, thread size, face type, property or material class, and coating requirement separately.

2. Flange and bearing-face options

Both products have smooth and serrated variants. For the DIN 6923 nut, the serrated bearing face helps prevent loosening under vibration. For the DIN 6921 bolt, the smooth bearing surface is standard and serrated versions are an option where additional locking grip is required.

3. Size and dimensional information

The approved DIN 6923 material gives a technical range of M4 to M20 and a dimensional matrix for M5, M6, M8, M10, M12, M14, M16, and M20. Its listed maximum flange diameters range from 11.8 to 42.8, heights from 5.0 to 20.0, and across-flats dimensions from 8.0 to 30.0. The excerpt presents these values in millimetres, although the table labels should still be checked against the current technical data sheet before release for a specific order.

The DIN 6921 material documents a metric range of M5 to M20 and provides dimensional examples for M6, M8, M10, and M12. The listed maximum flange diameters are 14.20 mm, 18.00 mm, 22.30 mm, and 26.60 mm respectively; the listed wrench sizes are 10 mm, 13 mm, 15 mm or 16 mm, and 18 mm; and the listed maximum head heights are 6.60 mm, 8.10 mm, 9.20 mm, and 11.50 mm.

These are not like-for-like dimensions: the nut table reports flange diameter, nut height, and across-flats size, while the bolt table reports flange diameter, wrench size, and head height. A buyer should use the applicable component drawing rather than compare a nut height directly with a bolt head height.

4. Property classes and material options

The DIN 6923 nut has property classes 8, 10, and 12. Steel chemical verification supports maintaining ISO 898-2 Class 10 integrity.

The DIN 6921 bolt has property classes 8.8, 10.9, and 12.9 and stainless-steel options A2-70 and A4-80.

The two excerpts use different class presentations. Procurement should confirm the required designation, mating component class, and applicable standard in the order documentation rather than assume that a nut class and bolt class are numerically interchangeable.

5. Surface finishes and documentation

The DIN 6923 nut has zinc plating to ISO 4042, zinc flake to ISO 10683, and hot-dip zinc to ISO 1461 or ISO 10684. Its surface treatment is verified, and salt-spray testing follows ISO 9227 within its risk-management description.

The DIN 6921 bolt has zinc-nickel, Dacromet, and Geomet finishes. These options address corrosion requirements.

The DIN 6923 nut has full MTC 3.1 traceability, dimensional verification against DIN 6923 / ISO 4161 gauges, and digital batch tracking.

For the DIN 6921 product page, see DIN 6921 Hexagon Flange Bolts.

6. Procurement decision points

Use the following checklist when comparing a hexagon nut with flange with a DIN 6921 flange bolt in a bill of materials:

1. Identify the component role: specify whether the line item is the DIN 6923 nut or DIN 6921 bolt.
2. Confirm the thread size: select a documented metric size and verify it against the current drawing or TDS.
3. Confirm the bearing face: state smooth or serrated rather than assuming the face type from the standard name alone.
4. Match the class and material record: request the applicable property class, steel grade, or stainless designation for the complete joint.
5. Define the finish: name the required coating or treatment and request the applicable compliance documents.

Conclusion

The DIN 6923 hexagon nut with flange and DIN 6921 hexagon flange bolt address different positions in a flanged fastening joint. The products share an integrated flange and smooth or serrated face options but have different dimensions, class designations, material options, and finishes.