Screw locking
For maximum security
Nord-Lock® wedge-locking washers are machine elements with a mechanical action. They have wedges on the inner surface and radial ribs on the outside. Under vibration, they secure screw connections by means of a locking mechanism rather than friction. This makes Nord-Lock® wedge-locking washers superior to conventional screw locks.
Plus factors
Nord-Lock® effectively prevents spontaneous loosening – even under strong vibration and dynamic stress.
The unscrew locking action is guaranteed for both dry and lubricated surfaces.
Our wedge washers can be assembled and disassembled quickly and easily. Nord-Lock® connections do not need retightening.
Nord-Lock® achieves maximum security even at low pre-tension levels.
Nord-Lock® screw locking system is reusable. It is available in a variety of materials and coatings.
The Nord-Lock® screw locking system is officially approved and well-proven in use – including in the construction and railway sectors.
Method and principle
Nord-Lock® consists of two identical wedge washers. These have wedges on the inside and radial ribs on the outside. The wedge surfaces of the washers, which are glued together in pairs, lie on top of each other when in use. The shape of the wedge surfaces is such that the angle between the lock washers is greater than the angle of the thread.
When you tighten the bolt or nut, the radial ribs of the Nord-Lock® washer are pressed tightly into the mating surface on the opposite side. The pair of washers stays securely in place. The only possible movement is between the wedge surfaces. The wedge effect increases the clamping force at the slightest unscrewing rotation: the screw locks itself.
Installation and use
Nord-Lock® wedge-locking washers are suitable for all screw strength classes up to and including 12.9. Whether you need to use them for threaded holes (1), counterbored holes (2), through holes (3) or studs (4) – the locking washers offer a wide range of flexible and multifunctional applications. Two pairs of locking washers should be used for through holes. We also recommend that you use Nord-Lock® washers with an enlarged outer diameter for slotted holes and soft mating materials. Do not use Nord-Lock® on unsecured backing washers!
Nord-Lock® washer pairs are the ideal solution wherever screw connections might otherwise work themselves loose. For over 30 years, Nord-Lock® has guaranteed maximum security against loosening, even under strong vibrations and dynamic stress.
Proof perfect
The Junker vibration test in accordance with DIN 65 151 is an excellent method for testing and comparing the security of screw connections under dynamic stress. A pressure cell continuously measures and records the pre-tensioning force while the screw connection is subjected to stress at right angles to the thread axis.
The Junker diagram shows Nord-Lock®'s unique locking effect. Only minor pre-tensioning force losses occur due to normal settlement processes between the parting lines and the thread. The wedge-locking action is confirmed by the significant increase in clamping force during the loosening process. Conventional locking elements do not display locking action when subjected to vibration.
Information and more
Interested in NORD-LOCK® wedge-locking washers? Please download further information here.
