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stainless wear

stainless wear

stainless wear

(OP)
   I have a 316 L shaft acting as a push rod, that rides in a sleeve. The sleeve is of an unknown alloy, mabey brass. I Would like to make a new sleeve out of 316 L (the old sleeve wears out fast). It was suggested to me that having the stainless together would be bad because one part of two moving parts needs to be softer than the other. Does anybody think the stainless together would be a problem? If so why? This is on a rotary filler.

RE: stainless wear

Your first obstacle to overcome with 316L vs 316L is galling. This is about the worst selfmated couple you can get.

Comeback with a little more information on your setup is there any lubrication, the environment, and speed of your shaft, etc.

RE: stainless wear

(OP)
This shaft moves up and down about 6 inches about 4 to 5 times per minute, there is a daily lubrication schedule and we use food grade grease.

RE: stainless wear

(OP)
Also the environment is wet and acidic fron tomato based products.

RE: stainless wear

My guess is that the 316 shows some pitting corrosion damage.  You can do a number things to help you out.
You probably should go to a higher alloy stainless (and higher strength) for the shaft.  I would also suggest a non-metalic bushing.  There are some very good high performance plastic bearing materials out there (my favorites are from Victorex).

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm

RE: stainless wear

Rubbing two pieces of stainless steel together can cause galling, especially at high speeds.  One part (the sacrificial one) can be make of softer non-galling material.  This material is often used in positive displacement pumps as material for the rotors.  2 materials come to mind as non-galling stainless steel.

ILLIUM 8
Waukesha 88

RE: stainless wear

These are non-galling also:

Carpenter Galltough

Fry Steel Nitronic 60

RE: stainless wear

zipthetrip,

Food grade grease might be Crisco shortening as lubricant?

Getting a sleeve in FDA approved plastic (white color) and good wear characteristic would be the key.  

The conditions do not seem to be hot or severely corrosive.  The clean-in-place wash cycles are probably the most harsh conditions for the sleeve.

You might be able to make a good sleeve of 316 SS by adding a wear resistant coating of silicon carbide ceramic (plasma arc spray).  Some centrifugal pump users specify the ceramic coating to minimize the wear under a Teflon ring seal on SS shaft.  

It might depend on the shaft diameter as to how practical it would be to get the ceramic coating inside the sleeve or onto the shaft contact area.
  

RE: stainless wear

Postive displacement pump users on the food industry use a special non-galling stainless steel material because the pump rotor and housing often bump and rub during operation.  They use a material called ILLIUM 8 for the rotor because it is easier to replace than the whole housing.  When they have to use 316L rotor material they increase the clearance in the pump from .001" to .005" to avoid contact between the two parts.

John Reinbold
"Chance favors the prepared mind"
www.stainlessfoundry.com

RE: stainless wear

If non-metallic materials may be your choice.
You may want to check out fiberglass filled chemloy. Vespel may be another choice that does not require any lubrication at all. You have to check with the design guide for these matterials with the manufacturer or distributor of these materials as bushing or bearing products.

RE: stainless wear

316 on 316 often causes galling when rubbed against each other.  Make the sleeve out of non-galling stainless such as ILLIUM 8 or Waukesha 88.  Both are food grade materials.  Use the 316 on the shaft.

John Reinbold
"Chance favors the prepared mind"
www.stainlessfoundry.com

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