A Minimum Surface Finish Requirements For Bolted Joints? 1

[fsincox]

I believe I had been told once by a senior engineer that for a bolted joint to stay properly torqued the mating surfaces should have a surface finish of at least 125, we were having lots of "bolts shaking loose" problems and only required 250. Is there a reference for this?
Frank

 

[ctopher]

I'm not familiar with a surface texture for bolts.
If you have bolts shaking loose, you may need lock washers or lock wire...or both.

Chris
SolidWorks 11
ctopher's home
SolidWorks Legion

 

[MintJulep]

Sounds like you have encountered the phenomenon known as embedment.

The peaks of you rough surface tend to get flattened over time, and the thickness of the material being clamped by the fastener actually gets less, resulting in a loose fastener.

You'll find some discussion on the subject in forum725.

Google "threaded fasteners embedment" will return plenty of useful information as well.