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Machine Designer Suffers Stainless Steel Galling

I am looking at galling of stainless steel. I have a shaft with a key-way, the shaft material is 303Se, Condition A, per ASTM A582 . The key-pin is 440C, per ASTM A276 and heat treated to Rc 54 or higher ref SAE AMSH6875. The key-way causes the shaft to rotate as the pin moves axially up the shaft. I have considerable galling of the shaft keyway walls. I need the parts to be corrosion proof while reducing the galling. Any suggestions?

Pat Olstad
Aerospace - Phoenix, Arizona
2003

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Galling would be manifested by a tearing out of the shaft wall due to cold welding. Usually it doesn't happen if one component is substantially different in structure than the other and harder than the other. The fact that the keyway is becoming damaged is not by itself proof that the problem is galling. It is common for even simple keyways to become "hogged out" by a key due to heavy loading, and with a cold-working material like 303 it sounds possible that some distortion could happen early on, then stop as the material became cold worked. Has any kind of metallurgical examination substantiated that the problem is galling rather than overloading? Is there any indication of shaft wall material "sticking" to the key pin or vice versa?

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

We process a co-deposit of Electroless-Nickel with particles of P.T.F.E.(Teflon) which is used in numerous applications to prevent wear and galling. The Nickel is hard and corrosion resistant and the addition of microscopic particles of Teflon provide self-lubricity.

Charlie Camenzind
- Phoenix, Arizona
2003

Consider E-Coating stainless to prevent galling.

Glen J. Bartolotti
- Arlington, Washington
2005

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January 13, 2010

I think that you should change the method, consider to use keyless joint, please check the article in Machine Design
machinedesign.com/article/a-simple-rotary-joint-0804

good luck

Jay Shu
- Winston, Georgia

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Hi, Jay. Pat seems to be describing a shaft that has a keyway running the length of it, which keyway is not straight but comprises a helix or a sort of screw thread, such that as a pin moves up and down the shaft, the shaft is forced to rotate -- comprising a simple machine for translating axial thrust along the shaft into rotation of the shaft. Thanks for participating, but unless I am misunderstanding, the cited article about a keyless coupling doesn't seem to have much to do with Pat's problem. Thanks again.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
January 13, 2010