Technical Term for Bolt Backing Out? 4

[JakeAdkins]

Is there a more technical way of saying that a bolt is backing out?

I am writing a service bulletin and want to let the customer know that a bolt tends to back out over time.

 

[ornerynorsk]

Why is it backing out? Reciprocation of adjoined parts, vibration, axial forces, etc. Customer might appreciate the reasoning behind needing to check a bolt periodically, and could feasibly be more inclined to do so with a valid reason stuck in their mind.

 

[CorBlimeyLimey]

Loosening ?

 

[JohnGP]

Yes, "loosen" does it for me.

 

[JakeAdkins]

It is backing out due to vibration. We are including a perminate fix we designed

 

[MiketheEngineer]

Bolt is loosening itself
Bolt is loose
Bolt is unscrewing
Premature bolt extraction
Bolt doesn't want stay put


Best I can do

 

[JakeAdkins]

I like the last on Mike

 

[CoryPad]

The terms loosening and self-loosening are used in technical journal articles on this subject. Bickford, in An Introduction to the Design and Behavior of Bolted Joints refers to self-loosening. Sakai, in Bolted joint engineering, refers to rotational loosening. And VDI 2230 Systematic calculation of high duty bolted joints uses the term loosening by rotation.

 

[IRstuff]

That last one is food for thought. Can a bolted joint loosen by other that rotation?

TTFN

FAQ731-376

 

[MintJulep]

Yes it can. The plies in the joint can get thinner due to cold flow, creep or other mechanisms. This is called embedding.

The fastener can get longer due to creep or yield.

The the length's of things can change due to differential thermal expansion.

Loose bolt without rotation.

 

[CoryPad]

Great answer by MintJulep. The only other mechanism that I know is wear.

 

[IRstuff]

Thanks, MJ...

TTFN

FAQ731-376

 

[ShaggyPE]

How 'bout "decrease in preload" due to ????


-Dustin
Professional Engineer
Certified SolidWorks Professional
Certified COSMOSWorks Designer Specialist
Certified SolidWorks Advanced Sheet Metal Specialist

 

[Ron]

de-tensioning
relaxation
reversing

 

[MikeHalloran]

You gotta write for your audience, not for us.

e.g.:

"Dat dere sumbitch gon' back hissef right outta dere".




Mike Halloran
Pembroke Pines, FL, USA

 

[ScottyUK]

And where would that audience be... Compton?


----------------------------------

If we learn from our mistakes I'm getting a great education!

 

[MikeHalloran]

That would be South Louisiana.



Mike Halloran
Pembroke Pines, FL, USA

 

[rb1957]

"in-service vibration causes the bolt to loosen ..." i'd give the reader something of the story,

or you could use Mike's "vernacula" prose ...

 

[swall]

I have seen bolted joints lose clampload due to fatigue cracks developing in the thread roots of the bolts. Of course, failure was imminent at that point.

 

[Adalius]

Just out of curiosity, if the bolts are known to be doing this, has altering them via drilling a hole or replacing them with a predrilled bolt so they can be wire tied to prevent rotation been considered?