Tension creates a self-locking bolt. Nord-Lock washers secure bolts with tension instead of friction.

The Junker vibration test

The Junker test is considered the most severe vibration test for bolted connections. In this video, we compare the performance of Nord-Lock washers with other locking methods. It will give you a clear indication of how wedge-locking washers work.

The loosening of bolted joints has been a problem ever since the bolt was invented, prompting numerous studies on the phenomenon. In the 1960s, German professor Gerhard H. ­Junker discovered that shear loading perpendicular to the fastener axis is the most severe form of loading for vibration-induced loosening. The testing method he devised, in which a joint is mounted on a test rig and exposed to a simulated vibration at a right angle to the joint, subsequently became a DIN standard – DIN 65151 – and is commonly known as the Junker test.

To prove the reliability of its products, Nord-Lock runs 10 000 Junker demonstrations worldwide every year, in the presence of its customers. In addition, nearly 100 customer-specific Junker tests are carried out in Nord-Lock’s laboratories every year.