Bearings & Bushings for Underwater Use w/o Housing | Get Details

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Discussion Overview

The discussion revolves around the search for bearings or bushings that can operate underwater without housing, focusing on their resistance to rust and corrosion in various water conditions, particularly saltwater. Participants explore different materials and their suitability for long-term underwater applications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about bearings or bushings that can function underwater without housing and with minimal rust.
  • Another suggests stainless steel bearings, noting that oxidation may be less of a concern than lubrication in underwater environments.
  • A participant expresses skepticism about stainless steel's rust resistance, particularly for long-term underwater use, and emphasizes the need for lubrication.
  • Discussion includes the importance of the type of stainless steel, with Stainless 316 mentioned as a marine-grade option that offers high corrosion resistance, though not completely corrosion-proof.
  • Concerns are raised about galvanic corrosion in saltwater environments, prompting a request for clarification on this issue.
  • Participants discuss the use of seals, o-rings, and gaskets as best practices for underwater bearings to retain lubrication.
  • One participant expresses frustration over the lack of options for bearings or bushings that can operate without sealing in underwater conditions.
  • A specific polyacetal bushing from Misumi is mentioned as a potential option, with questions about its compatibility with saltwater and a stainless steel shaft.
  • Another participant suggests contacting Misumi Customer Service for specific guidance on the polyacetal bushing's suitability.
  • Examples of existing underwater mechanisms using saltwater-impervious bushings are cited, raising questions about the materials used in those applications.
  • There is a mention of Lignum Vitae as a potential material for underwater applications.
  • Ceramic bearings are noted for their saltwater resistance, although they may only be available in smaller sizes.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a specific solution for bearings or bushings that can operate underwater without housing. Multiple competing views and uncertainties regarding material suitability and application specifics remain evident throughout the discussion.

Contextual Notes

Participants highlight the importance of application specifics, including the type of water and the need for lubrication, which remain unresolved in the discussion. There is also a lack of definitive information on the performance of suggested materials in saltwater environments.

malek340
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I'm currently finding a bearing or bushings that can work underwater without a housing with minimal rust. Do anyone have an idea if it can? If there is, pls give me the details of the bearings or bushings?
 
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It's hard (or impossible) to give you really useful feedback without some sort or information about the application... but I'll wager a guess at stainless steel bearings? I think oxidation will be less of a problem than lubrication under water though.
 
But won't stainless steel still rust that fast? I resesrched and found that it still rust. My application would be using a bearing or bushing that is attached to a shaft for a motor tp run underwater. The equipments will be placed underwater for quite a long time
 
It depends on what stainless you're using, and what the "water" is (I'm assuming you mean salt water?). Stainless 316 is a marine-grade stainless steel and pretty tough stuff. It could give you a pretty high resistance to corrosion, but no stainless is 100% corrosion proof.

Of course if you're talking salt water (or any electrolyte), you also need to worry about Galvanic Corrosion. Are you aware of the difference?

http://en.wikipedia.org/wiki/Galvanic_corrosion
 
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Is there a known bearing that is made up from stainless steel 316? Btw bearings needs oil to be lubricated..So is it impossible to place it under sea water? Is there a way to use bearings underwater
 
Bearings are of course used underwater in all kinds of applications, as far as I know the "best practice" way to do it is to seal them from the water using o-rings and gaskets. This also allows retention of lubrication.
 
I'm seriously becoming desperate. I need a bushing or bearing that is able to work without sealing it. Is there really nothing that can work underwater just like that?
 
Shaft and bushing underwater

Recently i found a polyacetal bushing from Misumi and planning to use it for my underwater application(please do tell me if it can't be use when submerged in sea water). I'm planning to a attach it to a stainless steel shaft which will be rotated by a motor. Do u think it will work? Enlighten me pls.
 


malek340, To discover if your polyacetal bushing will survive the stainless steel motor shaft and the saltwater environment it seems to me the logical place to find out is Misumi Customer Service. If you are in the USA you might call them and ask:
MISUMI USA
1717 Penny Lane, Suite 200
Schaumburg, IL60173
USA
Phone 1: (847) 843-9105
Phone 2: (800) 681-7475

Cheers,
Bobbywy
 
  • #10
There are lots of mechanisms already rotating shafts underwater through a saltwater-impervious bushing. Ships, boats, outboard motors, pumps, directional sonar arrays are just a few examples. What do they use?
 
  • #11
I just recently found out about polyacetal bushing but am not too sure yet. Any thoughts?
 
  • #12
There's just no way to give you any more specific information without knowing SOMETHING about your application...
 
  • #13
Have you thought about Lignum Vitae?
 
  • #14
Ceramic bearings are becoming pretty routine and should be quite salt water resistant.
However, I believe they are currently offered primarily in small sizes.
 

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