Illustration of the washer pair principle; not a photograph of a specific product.
How a Nord-Lock washer pair works
Nord-Lock Original wedge-locking washers secure bolted joints against self-loosening under vibration. They work as a pair: the cam faces point inward towards each other, while the fine radial serrations face outward against the mating surfaces.
When correctly installed, the outer serrations engage the mating surfaces. If the joint tends to loosen, relative movement across the inner cam faces creates a wedge effect that opposes loosening.
1 pair = 2 cooperating washers. One separate half is not a complete locking element. Please specify quantities in pairs.
Materials and configurations
- Steel: through-hardened EN 1.7182 with a zinc flake coating. Designations NL and NL…sp. Zinc flake coating is distinct from zinc plating.
- A4 stainless steel: EN 1.4404, the manufacturer’s surface-hardened ss configuration. Designations NL…ss and NL…spss.
Standard outer diameter and enlarged SP diameter configurations have separate dimensions. SP provides a wider bearing area; suitability depends on the bolt head or nut, hole geometry and mating material.
Washer hardness is distinct from bolt property class. Washers must be harder than the mating surfaces so the outer serrations can engage correctly. Select the material with regard to the environment and other joint components. Nord-Lock manufacturer technical information.
Catalogue dimensions
Metric overview of Nord-Lock Original from the manufacturer’s manual: two steel washer tables grouped by application. Enlarged SP washers (M3.5–M36) are listed for hexagon heads, and standard washers (M3–M130) for socket head cap screws, such as DIN 912. For the same bolt size, the standard washer has a smaller outer diameter than SP: for M10, NL10 is Ø 16.6 mm and NL10sp is Ø 21 mm. Select the specific pair according to bolt diameter and the bearing area of the head or nut. The tables do not list A4 stainless steel dimensions.
Thickness T is the thickness of the complete assembled pair, not one washer half. Product designations follow the manufacturer’s catalogue. “For bolt” gives the nominal bolt size; the washer hole has no thread.
| Designation | For bolt | Inner diameter [mm] | Outer diameter [mm] | Pair thickness T [mm] |
|---|---|---|---|---|
| NL3.5sp | M3.5 | 3.9 | 9 | 1.8 |
| NL4sp | M4 | 4.4 | 9 | 1.8 |
| NL5sp | M5 | 5.4 | 10.8 | 1.8 |
| NL6sp | M6 | 6.5 | 13.5 | 2.5 |
| NL8sp | M8 | 8.7 | 16.6 | 2.5 |
| NL10sp | M10 | 10.7 | 21 | 2.5 |
| NL12sp | M12 | 13 | 25.4 | 3.4 |
| NL14sp | M14 | 15.2 | 30.7 | 3.4 |
| NL16sp | M16 | 17 | 30.7 | 3.4 |
| NL18sp | M18 | 19.5 | 34.5 | 3.4 |
| NL20sp | M20 | 21.4 | 39 | 3.4 |
| NL22sp | M22 | 23.4 | 42 | 4.6 |
| NL24sp | M24 | 25.3 | 48.5 | 4.6 |
| NL27sp | M27 | 28.4 | 48.5 | 5.8 |
| NL30sp | M30 | 31.4 | 55 | 5.8 |
| NL33sp | M33 | 34.4 | 58.5 | 5.8 |
| NL36sp | M36 | 37.4 | 63 | 5.8 |
The tables show catalogue dimensions, not current JENPEX stock. Availability of the required size, material and configuration will be confirmed upon enquiry.
| Designation | For bolt | Inner diameter [mm] | Outer diameter [mm] | Pair thickness T [mm] |
|---|---|---|---|---|
| NL3 | M3 | 3.4 | 7 | 1.8 |
| NL3.5 | M3.5 | 3.9 | 7.6 | 1.8 |
| NL4 | M4 | 4.4 | 7.6 | 1.8 |
| NL5 | M5 | 5.4 | 9 | 1.8 |
| NL6 | M6 | 6.5 | 10.8 | 1.8 |
| NL8 | M8 | 8.7 | 13.5 | 2.5 |
| NL10 | M10 | 10.7 | 16.6 | 2.5 |
| NL11 | M11 | 11.4 | 18.5 | 2.5 |
| NL12 | M12 | 13 | 19.5 | 2.5 |
| NL14 | M14 | 15.2 | 23 | 3.4 |
| NL16 | M16 | 17 | 25.4 | 3.4 |
| NL18 | M18 | 19.5 | 29 | 3.4 |
| NL20 | M20 | 21.4 | 30.7 | 3.4 |
| NL22 | M22 | 23.4 | 34.5 | 3.4 |
| NL24 | M24 | 25.3 | 39 | 3.4 |
| NL27 | M27 | 28.4 | 42 | 5.8 |
| NL30 | M30 | 31.4 | 47 | 5.8 |
| NL33 | M33 | 34.4 | 48.5 | 5.8 |
| NL36 | M36 | 37.4 | 55 | 5.8 |
| NL39 | M39 | 40.4 | 58.5 | 5.8 |
| NL42 | M42 | 43.2 | 63 | 5.8 |
| NL45 | M45 | 46.2 | 70 | 7 |
| NL48 | M48 | 49.6 | 75 | 7 |
| NL52 | M52 | 53.6 | 80 | 7 |
| NL56 | M56 | 59.1 | 85 | 7 |
| NL60 | M60 | 63.1 | 90 | 7 |
| NL64 | M64 | 67.1 | 95 | 7 |
| NL68 | M68 | 71.1 | 100 | 9.5 |
| NL72 | M72 | 75.1 | 105 | 9.5 |
| NL76 | M76 | 79.1 | 110 | 9.5 |
| NL80 | M80 | 83.1 | 115 | 9.5 |
| NL85 | M85 | 88.1 | 120 | 9.5 |
| NL90 | M90 | 92.4 | 130 | 9.5 |
| NL95 | M95 | 97.4 | 135 | 9.5 |
| NL100 | M100 | 103.4 | 145 | 9.5 |
| NL105 | M105 | 108.4 | 150 | 9.5 |
| NL110 | M110 | 113.4 | 155 | 9.5 |
| NL115 | M115 | 118.4 | 165 | 9.5 |
| NL120 | M120 | 123.4 | 170 | 9.5 |
| NL125 | M125 | 128.4 | 173 | 9.5 |
| NL130 | M130 | 133.4 | 178 | 9.5 |
The tables show catalogue dimensions, not current JENPEX stock. Availability of the required size, material and configuration will be confirmed upon enquiry.
Dimension source: Nord-Lock Original – manufacturer’s user manual 2026, page 5 (PDF). Values are nominal; consult the manufacturer for tolerances and precise application conditions.
Installation and joint selection
- Install the pair with the cam faces together and the serrations facing outward. Use the correct size and stable mating surfaces.
- For a bolt in a tapped hole, place a pair under the head. For a through bolt with a nut, use one pair under the head and a second pair under the nut.
- Before tightening a through joint, close the cams of both pairs as instructed. Hold one fastener against rotation while tightening the other.
- Do not add a loose flat washer underneath a locking pair without assessing the joint: another movable mating surface can compromise the locking function.
- The standard configuration is not automatically suitable for a left-hand thread, which requires customized washers. Freely rotating mating surfaces, surfaces harder than the washers, very soft materials and joints with large settlements are also unsuitable.
Determine tightening torque, lubrication and any reuse according to the manufacturer’s current instructions and the condition of the individual components. A single universal torque is not appropriate for all joints. Current Nord-Lock Original installation guide.
Related washers
DIN 125 – classic flat washers and DIN 9021 – large series flat washers provide a bearing area and distribute pressure. Nord-Lock is a locking pair that uses a wedge effect. These products perform different functions and are not automatically interchangeable.
Need Nord-Lock washers for a specific joint?
Send us the bolt size or washer designation, required material and number of pairs. When replacing an existing product, include its designation or technical data sheet.
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