Your result
Locking ability |
1 out of 5 |
Reusability |
Not Applicable |
Worker safety |
4 out of 5 |
Initial cost |
Low |
Lifetime cost |
High |
Locking ability |
1 out of 5 |
Reusability |
Not Applicable |
Worker safety |
4 out of 5 |
Initial cost |
Low |
Lifetime cost |
High |
Tooth lock washers (electrical contact washers) are designed to prevent bolted joints from loosening using friction. Similarly to serrated washers, tooth lock washers feature teeth-like-serrations either internally or externally. They are installed between the bolt head/nut and the mating surface, and the bolted joint is then tightened in the same way as an unsecured nut. When the bolted joint is tightened, these teeth bite into the mating surface.
These washers work best with soft surfaces as hard surfaces will flatten the teeth – preventing them from successfully biting into the surface and securing the joint.
Read the full version in the eBook "Why do bolts loosen?"
(A comparison between common bolt securing options)
Scroll down to access the ebook.
The biggest challenge for a bolted joint, causing it to lose preload and fail, is spontaneous loosening often caused by vibrations. This Junker test shows all 5 nuts rotated loose! A steep decline in the graph indicates a failure. Read more about the Junker Test.