Bolt securing system



Applying appropriate stud torque Nord-Lock® bolt securing system guarantees stable tensile load in the screw stem even in case of strong loosening effects such as vibrations, dynamic loads, etc. The product itself is a pair of washers to provide wedge-locking according to standard DIN 25201. Nord-Lock® washers have to be placed directly between the surface and bonding unit without using any other washers.

When the screws and / or the nut is tightened, radial teeth on the external surface of washer grip and seat into the mating surface locking the two half-pair of washers in place and internal cams with rise are engaged. After tightening, movement to loosening direction is allowed only across the face of the cams.

Nord-Lock uses tension instead of friction, they come pre-assembled in pairs. On the inner side of washers have cams with rise which is bigger than the pitch of the bolt. On the outer opposing side radial teeth take place which functionally fix the washers to surface during tightening. Thanks to all of these features even slight rotation occurs in loosening direction, washers try to move on the cams resulting additional tension created in the bolt to make the joint self-locking. Every loosening attempt is eliminated by wedge action of inner cams.

Nord-Lock washers provide secured joint in case of vibrational circumstances and impulsive dynamic loads as well.


Tests substantiate the benefits of Nord-Lock® bolt securing system benefits:

  • provide safe bolted connection even regular dynamic loads occur
  • lubricant does not have an effect on tightness of joint
  • resists the loosening effects caused by vibrations
  • screw joint can be installed easily and fast
  • after dismantling Nord-Lock washers are reusable some time
  • self-locking effect is independent from tightening torque

Efficiency of screw connection can be inspected and demonstrated by Junker vibration test equipment and the corresponding computer program. The Junker test investigate behaviour of standard M8 screw joint with dynamic load in case of usage of different types of screw securing methods such as Nord-Lock bolt securing, slit ring, claw washer, nylon inserted nut.

Junker vibration test curves:



  Nord-Lock sizes:
  • Delta-protect coated steel (ELV, RoHS compliance): M3-M130
  • stainless steel (SS 2343): M3-M80
  • normal and increased external diameter


For further information about full range, technical data and allowed assembly methods find Nord-Lock Hungarian catalogue is available for download in PDF format from our site.