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A serrated face nut is a locknut with ridges on the face of the nut that bite into the surface it is tightened against. The serrations are angled such that they keep the nut from rotating in the direction that would loosen the nut. Due to the serrations they cannot be used with a washer or on surfaces that cannot be scratched. Sometimes both faces of the nut are serrated, permitting either side to lock.
A serrated face nut is a locknut with ridges on the face of the nut that bite into the surface it is tightened against. The serrations are angled such that they keep the nut from rotating in the direction that would loosen the nut. Due to the serrations they cannot be used with a washer or on surfaces that cannot be scratched. Sometimes both faces of the nut are serrated, permitting either side to lock.
See also
*Serrated flange nut
A flange nut is a nut that has a wide flange at one end that acts as an integrated washer. This serves to distribute the pressure of the nut over the part being secured, reducing the chance of damage to the part and making it less likely to loosen ...
References
Nuts (hardware) {{Mech-engineering-stub