A wider area for distributing bearing pressure
DIN 9021 flat washers have a larger outer diameter. Beneath a bolt head or nut, they provide a wider bearing area and help distribute pressure over a larger part of the connected component.
Compared with a standard DIN 125 washer for the same bolt, the outer profile is wider. Selection also depends on thickness, hardness and the mating material; a larger diameter alone does not guarantee a higher load capacity for every joint.
These washers are also marketed as washers for rivets, but their use is not limited to riveted connections. Not every wide or body washer corresponds to this configuration.
Materials, hardness and surface finishes
The overview covers steel, stainless steel A2 and stainless steel A4. Washer hardness, material and surface finish are separate specifications. Depending on the product, documented steel options are 140 HV or 200 HV; 200 HV stainless configurations are documented only for selected sizes.
| Material | Washer hardness | Documented surface options |
|---|---|---|
| Steel | 140 HV | Plain, zinc-plated, hot-dip galvanized, zinc flake coating |
| Steel | 200 HV | Zinc-plated, zinc flake coating; black zinc flake coating on selected items |
| Stainless steel A2 | 200 HV for selected sizes; otherwise according to the configuration | Stainless configuration; finish specified for the selected product |
| Stainless steel A4 | 200 HV for selected sizes; otherwise according to the configuration | Stainless configuration; finish specified for the selected product |
Each combination has a different size range. The table does not imply that every material, finish and hardness is offered in every size. Hardness for a stainless configuration without a stated value will be checked against the specific product.
HV describes washer hardness, not bolt property class. Plain steel is not automatically black oxide treated. A zinc flake coating is distinct from zinc plating.
Washer dimensions
For bolt gives the nominal bolt diameter. d1 is the actual hole diameter and d2 is the washer outer diameter. The washer has no internal thread.
The table contains nominal catalogue dimensions of selected documented configurations in millimetres. Material and finish ranges differ; this is not a tolerance drawing or confirmation of standard compliance for a specific delivery.
| For bolt | Inner diameter d1 [mm] | Outer diameter d2 [mm] | Thickness [mm] |
|---|---|---|---|
| M2.5 | 2.7 | 8 | 0.8 |
| M3 | 3.2 | 9 | 0.8 |
| M4 | 4.3 | 12 | 1 |
| M5 | 5.3 | 15 | 1.2 |
| M6 | 6.4 | 18 | 1.6 |
| M7 | 7.4 | 22 | 2 |
| M8 | 8.4 | 24 | 2 |
| M10 | 10.5 | 30 | 2.5 |
| M12 | 13 | 37 | 3 |
| M14 | 15 | 44 | 3 |
| M16 | 17 | 50 | 3 |
| M20 | 22 | 60 | 4 |
| M24 | 26 | 72 | 5 |
| M30 | 33 | 92 | 6 |
| M36 | 39 | 110 | 8 |
The tables show catalogue dimensions, not current JENPEX stock. Availability of the required size, material and configuration will be confirmed upon enquiry.
Applications and selecting the right configuration
Large series flat washers are used in equipment assembly, sheet-metal connections, servicing and other joints that need a wider bearing area. Suitability for a particular mating material depends on joint design and the component’s resistance to compression or pull-through.
Check hole diameter, outer diameter, thickness, hardness, material and environmental conditions. A wide washer is not automatically suitable for every high-strength bolt. A flat washer alone does not secure the connection against loosening under vibration.
Related products
DIN 125 – classic flat washers have a standard outer diameter. DIN 9021 provides a wider bearing area. The configurations are not automatically interchangeable and should not be stacked without assessing the joint.
Looking for a specific DIN 9021 washer size?
Send us the required size, material, surface finish and quantity. For an engineered joint, include the required hardness or a drawing. We will check the appropriate configuration and availability.
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