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Re: Loose Bolts with DTI Washers

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>
> Split washers do not totally "collapse" in the true sense of the word.
They
> are flattened in the process of tightening and that sharp split "lip" will
> engage upon "backing off" in a soft nut.  A split washer if it "collapsed"
> would be perfectly flat once the nut pressure was removed.  Quite
obviously,
> this is not the case.
>

When you say 'collapsed', are you using that term to suggest Lock Washers
flatten plastically rather than elastically?  Because lock washers do
flatten completely at loads considerably less than bolt yield.  In fact,
they first collapse, and then rotate (roll) under higher load.  A
cross-section of one reveals why:  They are manufactured with a taper.

Yet, they do retain their spring (elastic) properties after flattening, and
subsequent release of clamping force.  Truth be told, lock washers are made
on the same piece of equipment used to make springs --- we just change the
lead and make a cut just short of one full revolution.  As for the 'lip'
that engages upon backing off --- if it does so -- we've never been able to
quantify any significant difference on vibration-loosening tests in the
laboratory.

David Sharp
TurnaSure LLC