Metal finishing Q&As since 1989

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What are effects of NaOH on 440 stainless steel bearings?

 

I have bearings that are made of 440 stainless steel. The system that they are being used in is subject to 1 percent NaOH caustic washdown. I am trying to find out what the effects of this washdown may have on the bearings.

Jon Coveyou
- Harbor Springs, Michigan

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I would expect 1 percent NaOH to have no effect at all on any grade of steel or stainless steel.

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

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First of two simultaneous responses --

As Ted says, the 440 stainless won't be affected by the sodium hydroxide DIRECTLY, but be aware that the caustic washdown will remove lubricant from the bearings. If they are designed to run without lubricant, no problem. But you might need to look to a re-lubrication system.

Bill Reynolds [deceased]
consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.
 

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Second of two simultaneous responses --

Jon:

I agree with Ted's opinion about the steels. They indeed resist 1% and more caustics. But are you talking about the material itself or the function of the bearing? If the operation is your concern then I immediately think about friction, about lubricants. You might have a problem. Caustic totally dissolves many of the usual ones. Then you might have to ask the lubricants experts. Bye.

Guillermo Marrufo
Monterrey, NL, Mexico