We have made a short video in which we ran 4 tests using a Junker test machine. These tests show the difference between connections using:

  1. A bolt and contra-bolt (DIN 934),
  2. A bolt with spring washer (DIN 127),
  3. A self-locking bolt (DIN 985) and
  4. A bolt with Nord-Lock washer.

This movie shows these fastened joints under the specific circumstances tested by this Junker test machine. Real-world examples where such conditions are experienced include the extreme vibrations found in heavy machinery such as trains, agricultural harvesting machines, and MRI machines used in the health care industry.

The chart that appears on the connected laptop shows the force applied by the bolt to the left on the y-axis - the more force, the sturdier the bolt is secured.

During the tests you see the force diminishing (relaxation), and the x-axis shows the elapsed time. We use an abbreviated test for the Junker test machine demonstration, so that you can see the process in a shorter time. In this case the test conditions were a 10-second duration, using a frequency of 40Hz.

The resulting graphs show that, for applications with heavy vibration, the use of Nord-Lock washers might be advisable. After an initial drop in force, the connection remains constant. This is because the two Nord-Lock washers are coupled with edged teeth that are slightly steeper than the pitch of the bolt. You need more force (see the end of the video) to turn the nut loose than it applies to the connection. Our sales advisors have a small kit for a manual demo where you can experience this effect yourself. Now you need fewer fastenings in your machine!

For more information about Nord-Lock, contact our sales advisors. Thank you Leonard for demonstrating the Junker test machine!

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