Wedge-locking solutions

Let geometry work for you

Nord-Lock wedge-locking products are recognized around the world for their ability to secure bolted joints exposed to severe vibration and dynamic loads. The system cannot loosen unintentionally as it creates a wedge underneath the bolt head/nut. An ideal solution for bolted joints where failure is not an option.

In addition to Nord-Lock wedge lock washers, the range also includes steel construction washers, wheel nuts, combi bolt washers and custom solutions.

  • The key is the difference in angles. Since the cam angle " α " is larger than the thread pitch " β ", the pair of wedge lock washers expand more than the corresponding pitch of the thread.

Tension makes the bolt self-locking

Nord-Lock wedge-locking technology secures bolted joints with tension instead of friction. The system comprises of a pair of lock washers that has cams on one side and radial teeth on the opposite side.

Nord-Lock wedge-locking products positively lock the fastener in a joint which is subjected to extreme vibration or dynamic loads.

  • When the bolt and/or nut is tightened the teeth grip and seat the mating surfaces. The Nord-Lock wedge lock washer is locked in place, allowing movement only across the face of the cams. Any attempt from the bolt/nut to rotate loose is blocked by the wedge effect of the cams.
  • When a bolt is untightened with a wrench, the pair of washers expand more than the corresponding pitch of the thread allows the bolt/nut to rise. Nord-Lock wedge lock washers positively secure the fastener in a joint which is subjected to any kind of vibration or dynamic loads.

Tension makes the bolt self-locking

The rise of the cams between the Nord-Lock wedge lock washers is greater than the pitch of the bolt. In addition, there are radial teeth on the opposite side. The wedge lock washers are installed in pairs, cam face to cam face.

Benefits of using Nord-Lock wedge-locking solutions

  • Maintains high clamp load and thereby ensures the function of the joint
  • Quick and easy to install and remove with standard tools
  • Locking function not affected by lubrication
  • Defined and uniform friction conditions which result in a more accurate preload
  • Same temperature characteristics as standard bolt / nut
  • Reusable – in addition, Nord-Lock wedge lock washers do not affect the reusability of fasteners
  • The washers are hardened and can support and distribute great loads
  • Washers with enlarged outer diameter available for flanged bolts / nuts
  • High corrosion resistance
  • Can be used with fasteners up to grade 12.9 (ASTM A574)
  • Reliable locking, even for joints with short clamp length
  • The Junker test, according to DIN 65151, is considered the most severe vibration test for bolted connections. During the test, the joint is exposed to transverse movements underneath the bolt head / nut, while the clamping force is continuously measured.

Proven in Junker vibration test

Nord-Lock locking washers are proven as a safe bolt securing system according to DIN 65151 tests performed by the independent research organisations IMA and CETIM. In addition, Nord-Lock personnel performs over 10,000 live Junker vibration tests around the globe every year.

The Junker test shows that Nord-Lock wedge lock washers safely secured the bolted connection; only a limited amount of tension is initially lost due to normal settlements. The wedge-locking function is verified through the clear increase in tension during untightening. All other bolt locking methods in the test failed to prevent loosening of the joint.

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  • Drawing of the test rig. The assembled parts are vibrated vertically and the joints are subjected to two impacts per cycle. The impacts are parallel to the bolt. The arrow displays the direction of vibration during the test. After testing, the fasteners are inspected for rotation.

Proven according to NASM impact & vibration test

The National Aerospace test, according to NASM 1312-7, is a test method originally developed by the U.S. military to test bolted connections’ resilience against impact and vibration.

Nord-Lock wedge lock washers are proven as a safe bolt securing system according to NASM 1312-7 tests performed by the independent organisation Det Norske Veritas (DNV). To view more certificates and type approvals, please visit Certificates.