Are tooth lock washers effective
against bolt loosening?
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)
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