Question on S/S Galling

[Pete_K]

i've been scouring the internet but have not found info on the exact scenario i am dealing with. I have a drum which rides on a central shaft. The hubs that ride on the shaft move axially along the shaft up to .5" due to expansion of the drum, so there is relative motion between the hubs and the shaft. If the hubs are 304, would i have a galling issue if the shaft were to be carbon, such as 1045?

Really appreciate any responses.

 

[EdStainless]

Different alloys with different hardness levels greatly reduces the chances of galling.
The surfaces should be as smooth as practical, and any lubrication will help greatly.
If you really need to keep them free moving I would suggest putting bushings of Nitronic 50 or 60 into the 304 hubs.
Heep the 1045 as hard as is practical.

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P.E. Metallurgy, Plymouth Tube

 

[Pete_K]

i should provide some background - this project replaced the previous drum which was all carbon steel. Details of the exact materials are unknown as the one drawing i had of the original was from pre-WWII, but my assumption is it was all low carbon.

 

[EdStainless]

Then I presume that you are moving to 304 to reduce corrosion?
If these are small make the hubs from Nitronic 50 or 60. These stainless grades have good corrosion resistance and excellent galling resistance.

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P.E. Metallurgy, Plymouth Tube

 

[Pete_K]

Yes, the salesman quoted them all S/S construction figuring it speaks something about our quality or knowledge of food equipment, (even though the carbon version lasted something like 70 years) but is turning into a pain. We also thought about using aluminum bronze sleeves in the hubs.

Thanks for you response.

 

[Pete_K]

In a scenario where the hubs were 304 and the shaft was 1045, would you expect a high likelihood of galling given a low surface pressure, say <500 psi and slow axial sliding?

 

[EdStainless]

No, if the loads are that low you are probably safe.
To be extra safe you should make sure that the finishing marks are both longitudinal.

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P.E. Metallurgy, Plymouth Tube

 

[Pete_K]

Thanks again, I really appreciate it.

 

[racookpe1978]

Galling problems I have to fix usually involve very high forces squeezing the tow parts together.

If this is a sliding fit that moves regularly, lubrication will greatly help. The low clamping" pressures of a sliding fit will reduce the tendency to gall.