What are Nord-Lock Washers?

The name Nord-Lock is actually a brand that is now becoming synonymous in industry with the term locking washers.

In simple terms, they are innovative locking washers that are sold in glued pairs. In contrast to other types of locking washers, Nord-Lock washers use tension rather than friction to achieve the lock.

So how do Nord-Lock Washers actually work?

Nord-Lock washers have a cam face on one side and radial teeth on the other side. When the matching faces are tightened, the radial teeth grip and lock the mating surfaces, with movement only possible across the cam face. A wedge effect is then created between the cams on the two cam faces and it is this tension that prevents the bolt from rotating loose.

Now for the science...

NORD-LOCK WASHERS

Because the angle of the cam “A” is greater than the thread pitch “B”, the two locking washers expand more than the pitch of the thread. It is this that creates the wedge effect which prevents the bolt or nut from coming loose.

As the bolt tightens, the radial teeth grab the mating surfaces. This locks the pair of washers in position – the only movement that can occur is across the cam faces.

The wedge effect of the cams prevents the bolt or nut from loosening at all.

How tight should bolts be tightened when using Nord-Lock Washers?

This really depends upon the size and grade of the bolt in question. The use of lubrication is also a factor.

If you are using Nord-Lock washers in place of a normal plain washer, as a general rule you should increase the tightening torque. This is because of the friction force beneath the bolt head that the washers add.

For more details on tightening torque we suggest you visit the Nord-Lock website.

Can they used with all bolt grades?

Nord-lock washers can be used with all common bolt grades including 12.9.

Can Nord-Lock washers be re-used?

Nord-Lock washers may be re-used, but not indefinitely. Also the type of use that the washers have been subjected to needs to be considered, for example the environment that they are used in and any potential external forces.

Before re-using Nord-Lock washers you should inspect the radial teeth and the cams to ensure that they are not heavily worn as this will affect their performance.

What is the purpose of the glue on the washers?

The glue on the washers purely serves to hold them together in the correct orientation, speeding up installation time and ensuring that the faces are correctly mounted.

What thread types and finishes are Nord-Lock washers available in?

Nord-Lock washers are available in metric or imperial options and they work with standard and fine threads. They won’t work with bolts which have a high pitch.

There are two choices of finishes – choose from A4-316 stainless steel or KL100 zinc flake coating (Delta Protekt). Delta Protekt increases the resistance to corrosion of iron and steel.