PPRuNe Forums - View Single Post - 737NGs have cracked 'pickle forks' after finding several in the jets.
Old 30th Sep 2019, 03:58
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WingNut60
 
Join Date: Dec 2010
Location: Perth, WESTERN AUSTRALIA
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Originally Posted by Scuffers
from an engineering perspective, using an in-situ sleeve is usually done then the stresses for the fixing exceed the properties of the host material, the sleeve's job is to spread the load over a larger area (assuming a cylindrical sleeve, the increase in diameter increases the load area in the base material).

the other way is to burnish the surface, typical burnishing tools are like a bar with many smaller rollers around it that then compress the host material to size, this is often done as the finishing process for bearing journals in aluminium used on camshafts etc.

here's some example tools: https://monaghantooling.com/precisio...ng/burnishing/
OK. I was already familiar with the "burnishing" process.
Your burnishing tool is what I am referring to as a roller reamer.
But I was not familiar with the use of the sleeve, which I now understand, in principle anyway.
Each roller of a roller reamer (burnishing tool) actually pushes a little bow wave of material ahead of it.
The hertzian contact stress so imposed has the potential, in itself to create microcracks, that potential could be obviated by use of the sleeve.
It also explains why the sleeves are not re-used.

I'm still interested to know whether the sleeve material is the same as or similar to the parent metal: harder or softer?
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