Nord-Lock Original Wedge-Lock Washers

A pair of wedge-locking washers that secures bolted joints with tension instead of friction. M3 to M130, five materials.

Section: Nord-Lock washers
Type: Nord-Lock Original

Overview

Bolted joints work loose under vibration and dynamic loads. Nord-Lock original washers stop this with tension instead of friction.

Each pair has cams on the inside faces and radial serrations on the outside. When tightened, the serrations bite into the bolt head or nut and the mating surface. Because the cam angle (α) is greater than the thread pitch (β), any movement can only happen across the cams, and that wedge effect keeps the preload and stops the bolt turning loose.

Every washer is laser marked with Nord-Lock, a traceable batch number and the material code. We supply the full range: steel, stainless steel, 254 SMO®, Alloy C-276 and Alloy 718, in regular and enlarged outer diameter (sp).

Specifications

Brand	Nord-Lock (Nord-Lock Group, Sweden)
Size range	M3 to M130; #5 to 5″
Materials	Steel EN 1.7182 · Stainless EN 1.4404 · 254 SMO® EN 1.4547 · Alloy C-276 · Alloy 718
Types	NL regular · NLsp enlarged outer diameter
Use with	Bolts up to grade 12.9 (steel washers), up to A4-80 (stainless)
Temperature	−50 °C to 200 °C (steel) up to −160 °C to 700 °C (Alloy 718)
Marking	Laser marked: Nord-Lock, batch number and type code
Warranty	Nord-Lock lifetime warranty

How it works

Tightening: the serrations embed and the cams stay closed — **Tightening**The serrations embed into the bolt head and the mating surface.

α > β

The cam angle α is steeper than the thread pitch β. To turn loose, the bolt would have to lift the joint, so it cannot.

Loosening attempt: movement only across the cam faces — **Loosening attempt**Movement only happens across the cam faces, so the preload is kept.

Proof under vibration

Typical result of a transverse vibration (Junker) test, DIN 65151: preload (kN) against load cycles. Illustrative curves.

Nord-Lock washer pair
Nylon insert nut
Spring washer
Plain nut and bolt

Choose the material

	Steel	Stainless steel	254 SMO®	Alloy C-276	Alloy 718
Applications	General steel applications	General stainless; no chlorides or acids	Salt water, chlorides, pumps, heat exchangers, desalination, food and medical	Acidic environments, chemical industry, offshore downhole	High temperatures: gas turbines, turbochargers, incinerators
Material	EN 1.7182	EN 1.4404	EN 1.4547	EN 2.4819 or eq.	EN 2.4668 or eq.
Size range	M3–M130 #5 to 5″	M3–M80 #5 to 3 1/8″	M3–M39 #5 to 1 1/2″	M4–M20 #8 to 1 1/2″	M4–M20 #8 to 1 1/2″
Corrosion resistance	1,000 h salt spray	PREN 27	PREN 45	PREN 68	PREN 29
Hardening	Through	Surface	Surface	Surface	Surface
Washer hardness	≥ 465 HV1	≥ 520 HV0.05	≥ 600 HV0.05	≥ 520 HV0.05	≥ 620 HV0.05
Bolt grades	Up to 12.9	Up to A4-80	Up to A4-80	—	—
Temperature	−50 to 200 °C	−160 to 500 °C	−160 to 500 °C	−160 to 500 °C	−160 to 700 °C
Designation	NL / NLsp	NLss / NLspss	NLss-254 / NLspss-254	NLss-276 / NLspss-276	NLss-718 / NLspss-718
Laser marking	flZn	SS	254	276	718

PREN = %Cr + 3.3 × %Mo + 16 × %N, for the base material. The mating surfaces must be softer than the washers for the locking to work. Temperature ranges are where the locking function is not affected.

Joint guide

**Tapped holes**One pair under the bolt head locks the bolt against the surface.

**Through holes**Two pairs: one under the bolt head, one under the nut. Turn both to close the cams first, and hold the nut while tightening the bolt.

**Stud bolts**A pair under the nut locks it on the stud, with no adhesive needed.

**Counterbores**The outer diameter of regular washers suits counterbores to DIN 974.

**Large or slotted holes, soft surfaces**Use a flanged bolt or nut with enlarged “sp” washers. For composites or heavy settlement, Nord-Lock X-series.

**Left-hand threads**Left-hand bolts need customised washers. Ask us.

Where Nord-Lock washers are not recommended

When the mating surfaces are not locked in place
When the mating surfaces are harder than the washers
On very soft surfaces such as wood and plastic
Where settlement is extremely large

Assembly: threaded holes

Put the pre-assembled pair on the bolt and fit the bolt in the threaded hole. Lubricate the thread and under the head first.
Tighten with a calibrated torque wrench to the Nord-Lock torque guideline.
Ready.

Assembly: through holes

One pair under the bolt head, the second pair under the nut. Lubricate the thread and under whichever part you turn.
Closed cams: correct
Open cams: not correct
Turn both the bolt head and the nut to close the cams on both pairs before tightening.
Hold one part still while tightening the other to the torque guideline.
Ready.