Root cause for damage to shaft and sleeve

[Mech5656]

Hello All,

We were recently assembling a pump and during installation of sleeve on shaft, the shaft got damaged. I have attached picture. The shaft and sleeve have clearance of 0.0005"-0.001" (Normal to me). During investigation, we found that:
• Shaft and Sleeve are 400 series stainless
• Shaft and Sleeve hardness is 5 Rc difference.

Can you comment on what can be the root cause? What can be done to avoid this in future?

 

[mfgenggear]

was it press on with out freezing the shaft & heating the sleeve?

 

[Mech5656]

Thanks for your reply.
No heat was involved. Clearance was 0.0005”-0.001”.

 

[GregLocock]

Stainless on stainless is well known for galling. You might have more luck if you use Copaslip on assembly.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[EdStainless]

What lube was used?
I would use a good lube and heat the sleeve a little (even 100C would help).
I'll wager that your sleeve isn't round, and that there was a high point or burr on those machined features.

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P.E. Metallurgy, consulting work welcomed

 

[mfgenggear]

@meck5656
More info please
Sleeve is a bearing?
Assembly was never run?
As mentioned what type of lube
What is the actual hardness of both details?
The damage was from installation?
.0005-.001 on diameter is .00025- .0005
Clearence per surface. As said before
Not a whole lot, that means both details
Have to be cylindricity .0001.
That is a very precise fit.
Since it was not thermally assembled. It would damge the details while assembly.
Reason it requires precision alignment.
And being both of the same material and near the same hardness will cause gauling.
And scratches.
It takes proper tooling to keep aligned.
And even force to assemble.

 

[mfgenggear]

Also to explain further due lack of clearence and may be the details were
slightly out of round. It is a tough
Assembly to install the sleeve with out binding. The sleeve being stiff and would not round up to the shaft , metal failed
Because it exceeded the hardness.

 

[Tmoose]

It looks like the parts galled during dis-assembly. Pulling the sleeve straight off the shaft.
The gall nugget "picked up" more and more material to make the big mess that extends into the shaft threads and beyond.

Might have been brand new damage during sleeve removal.
Might have been slight galling during installation, that was all too glad to resume it's mischief during sleeve removal.
Whoever was running the puller/press may have noticed the sleeve "getting tighter."

Mitigation attempts at assembly as mentioned by others.

Once the galling started, cutting the sleeve might have been the best solution.

 

[mfgenggear]

@Tmoose
yes agreed, compounded during disassembly

 

[DAVIDSTECKER]

Galling for sure.
Like metals, particularly stainless and aluminum seem to be the worst.
Anti-seize is your best bet.