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FULLERKREG DIN 9021 fender washers are manufactured from A2 stainless steel (SUS304) with a whitened and passivated surface finish. DIN 9021 specifies a large outer diameter washer — the outer diameter (d2) is approximately 3× the bolt nominal diameter, compared to approximately 2× for standard DIN 125A washers. This significantly larger bearing area distributes the bolt clamping load over a much greater surface, preventing pull-through and embedment in soft or thin materials such as wood, plastic, plywood, thin sheet metal, and composite panels.
The A2 (SUS304) material provides excellent corrosion resistance for outdoor, food-grade, and mildly corrosive environments, making these large-OD washers the preferred choice for timber construction, cladding, roofing, and outdoor structural applications where both large bearing area and corrosion resistance are required.
| Standard | DIN 9021 (Large OD flat washer, outer diameter ≈ 3× bolt diameter) |
| Type | Large outer diameter (fender / penny) washer — plain flat, no chamfer |
| Material | A2 Stainless Steel / SUS304 / 1.4301 |
| Surface Finish | Whitened & Passivated |
| Size Range | M5 – M24 |
| OD Ratio | Outer diameter ≈ 3× nominal bolt diameter (vs ~2× for DIN 125A) |
| Hardness | ≤ 200 HV |
| Corrosion Resistance | Good — suitable for outdoor, timber, and mild corrosive environments |
| Magnetic | Slightly magnetic after cold working |
| Recommended Pairing | A2 stainless bolts (DIN 931 / DIN 933) and nuts (DIN 934) for full material compatibility |
| Related Standard | DIN 125A (standard OD washer) | ISO 7093 (large washer series) |
| [Product Photo 1] | [Product Photo 2] | [Product Photo 3] | [Product Photo 4] |
All dimensions in millimeters (mm). Data per DIN 9021 standard, verified against reference data.
| Nominal Size (Bolt d) | d1 — Inner Ø (mm) | d2 — Outer Ø (mm) | h — Thickness (mm) | Weight (kg / 1000 pcs) |
|---|---|---|---|---|
| M5 | 5.5 | 15 | 1.0 | 0.72 |
| M6 | 6.4 | 18 | 1.6 | 1.96 |
| M8 | 8.4 | 24 | 2.0 | 4.35 |
| M10 | 10.5 | 30 | 2.5 | 8.40 |
| M12 | 13.0 | 37 | 3.0 | 15.0 |
| M14 | 15.0 | 44 | 3.0 | 21.0 |
| M16 | 17.0 | 50 | 3.0 | 27.0 |
| M20 | 21.0 | 60 | 4.0 | 53.0 |
| M24 | 25.0 | 72 | 4.0 | 76.0 |
* d1 = inner diameter (clearance hole); d2 = outer diameter; h = nominal thickness. All dimensions per DIN 9021. Weights are approximate based on A2 stainless steel density (7.93 g/cm³).
| Property | DIN 9021 (This Product) | DIN 125A (Standard) |
|---|---|---|
| Outer diameter ratio | ~3× bolt diameter | ~2× bolt diameter |
| M10 outer diameter | 30 mm | 20 mm |
| M12 outer diameter | 37 mm | 24 mm |
| Bearing area (M12) | ~940 mm² | ~320 mm² (~3× smaller) |
| Contact pressure (same load) | ~3× lower | Standard |
| Pull-through resistance | High — suitable for soft materials | Standard — for hard materials |
| Best for | Wood, plastic, plywood, thin sheet, composite panels | Steel, concrete, hard structural materials |
| ISO equivalent | ISO 7093 | ISO 7089 |
| Property | Value |
|---|---|
| Material Designation | A2 / SUS304 / 1.4301 / 0Cr18Ni9 |
| Chromium Content | 17.5 – 19.5% |
| Nickel Content | 8.0 – 10.5% |
| Tensile Strength | ≥ 500 MPa (annealed) |
| Hardness | ≤ 200 HV |
| Surface Finish | Whitened & Passivated |
| Corrosion Resistance | Good — suitable for outdoor, timber, food-grade, and mild chemical environments |
| Temperature Range | −50°C to +300°C (continuous service) |
| Magnetic | Slightly magnetic after cold working (stamping process) |
| Density | 7.93 g/cm³ |
Q: What is the difference between DIN 9021 and DIN 125A?
A: The key difference is the outer diameter. DIN 9021 specifies an outer diameter of approximately 3× the bolt nominal diameter, while DIN 125A specifies approximately 2×. For example, for M12: DIN 9021 has d2 = 37 mm vs DIN 125A d2 = 24 mm — giving approximately 3× greater bearing area. DIN 9021 is used where the larger bearing area is needed to prevent pull-through or embedment in soft materials. Both have the same inner diameter for the same bolt size.
Q: What materials are DIN 9021 fender washers suitable for?
A: DIN 9021 large OD washers are specifically designed for use with soft or thin materials where a standard DIN 125A washer would embed or pull through — including timber, plywood, OSB, MDF, plastic, GRP, polycarbonate, thin sheet metal, and composite panels. For hard materials (steel, concrete), standard DIN 125A washers are normally sufficient.
Q: Are A2 stainless DIN 9021 washers suitable for outdoor timber use?
A: Yes. A2 (SUS304) stainless steel provides good corrosion resistance for outdoor timber applications, including decking, fencing, pergolas, and garden structures. For coastal or marine-adjacent environments with high salt air exposure, A4 (SUS316) stainless washers provide superior corrosion resistance. Contact FULLERKREG for A4 DIN 9021 washer availability.
Q: What is the ISO equivalent of DIN 9021?
A: DIN 9021 is equivalent to ISO 7093 (large washer series). Both specify a large outer diameter washer with d2 ≈ 3× bolt diameter. DIN 9021 is the German national standard; ISO 7093 is the international equivalent.
Q: Can I use DIN 9021 washers with high-strength bolts (Grade 8.8 / 10.9)?
A: DIN 9021 A2 stainless washers have a hardness of ≤ 200 HV, which is the normal (soft) washer grade. For Grade 8.8 bolts in non-critical applications, this may be acceptable. For Grade 10.9 or 12.9 bolts, or for structural applications requiring accurate preload, hardened washers (300 HV minimum) should be specified. Note that DIN 9021 hardened washers are less commonly available — contact FULLERKREG for availability.
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