A flat washer for bolted connections
DIN 125 is a classic flat washer that distributes bearing pressure beneath a bolt head or nut over the mating surface. It helps protect the component surface during assembly and provides a suitable bearing area for the fastener.
This page covers form A without chamfer. The washer has no internal thread or locking mechanism; a plain washer alone does not secure a joint against loosening under vibration.
Materials, hardness and surface finishes
Material, hardness and surface finish are separate specifications. Depending on the individual item, steel configurations include 140 HV, 200 HV or 300 HV. Stainless steel is designated A2 or A4; 200 HV hardness is 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 | Plain, zinc-plated, hot-dip galvanized, zinc flake coating |
| Steel | 300 HV | Plain, zinc-plated, hot-dip galvanized, zinc flake coating |
| 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 |
The table shows options within the product group. Each combination of material, hardness and finish has its own size range; not every combination is offered for every M size. For stainless configurations without a stated hardness, we will check the specific product documentation.
HV denotes washer hardness, not a bolt or nut property class. Plain steel is not automatically black oxide treated, and a zinc flake coating is distinct from zinc plating.
Washer dimensions
For bolt identifies the nominal bolt diameter. The actual washer hole diameter is listed separately as d1; d2 is the outer diameter. The washer is not threaded.
The following are nominal catalogue dimensions of selected form A configurations in millimetres. Material and finish ranges differ. This table 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] |
|---|---|---|---|
| M1.6 | 1.7 | 4 | 0.3 |
| M2 | 2.2 | 5 | 0.3 |
| M2.2 | 2.4 | 6 | 0.5 |
| M2.5 | 2.7 | 6 | 0.5 |
| M3 | 3.2 | 7 | 0.5 |
| M3.5 | 3.7 | 8 | 0.5 |
| M4 | 4.3 | 9 | 0.8 |
| M5 | 5.3 | 10 | 1 |
| M6 | 6.4 | 12 | 1.6 |
| M7 | 7.4 | 14 | 1.6 |
| M8 | 8.4 | 16 | 1.6 |
| M10 | 10.5 | 20 | 2 |
| M12 | 13 | 24 | 2.5 |
| M14 | 15 | 28 | 2.5 |
| M16 | 17 | 30 | 3 |
| M18 | 19 | 34 | 3 |
| M20 | 21 | 37 | 3 |
| M22 | 23 | 39 | 3 |
| M24 | 25 | 44 | 4 |
| M27 | 28 | 50 | 4 |
| M30 | 31 | 56 | 4 |
| M33 | 34 | 60 | 5 |
| M36 | 37 | 66 | 5 |
| M39 | 40 | 72 | 6 |
| M42 | 43 | 78 | 7 |
| M45 | 46 | 85 | 7 |
| M48 | 50 | 92 | 8 |
| M52 | 54 | 98 | 8 |
| M56 | 58 | 105 | 9 |
| M60 | 62 | 110 | 9 |
| M64 | 66 | 115 | 9 |
| M72 | 74 | 125 | 10 |
| M76 | 78 | 135 | 10 |
| M80 | 82 | 140 | 12 |
| M90 | 93 | 160 | 12 |
The tables show catalogue dimensions, not current JENPEX stock. Availability of the required size, material and configuration will be confirmed upon enquiry.
Applications and selection
Flat washers are used in machinery assembly, equipment fastening, servicing and maintenance. Selection must account for bolt size, the hole in the component, bearing area, washer thickness and hardness, and environmental conditions.
A washer is not automatically suitable for every high-strength bolt. Required hardness and geometry depend on joint design and the documentation for the specific configuration. For soft materials, assess compression of the mating surface as well; adding a washer alone does not establish the joint load capacity.
Related products
DIN 9021 – large series flat washers provide a wider bearing area. The configurations are not automatically interchangeable and should not be stacked without assessing the joint.
Check materials, dimensions and joint requirements when selecting mating components. A related product is not an automatic recommendation for every combination.
Looking for a specific DIN 125 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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