×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Bearings/Bushing, Dry Film Lubrication, Grooving....

Bearings/Bushing, Dry Film Lubrication, Grooving....

Bearings/Bushing, Dry Film Lubrication, Grooving....

(OP)
The current bearing I'm dealing with is produced in house, and is made in a variety of sizes. The bearing is a multiple piece unit which incorporates a bushing, thrust washer, and a ball race (which retains our stationary peice to our peice in motion).

The bushing (kinda a misnomer, we just refer to it as the bushing) is a journal bearing, made from a Beryllium Copper alloy C17200 with about a 41HRc. We press this into the peice in motion with a .003" interference fit. We currently plate the bushing with silver .001" (+/-.0002") thick.

An example size of this bushing is 2.003" OD x 1.875" ID x .625" WIDTH.

What benefits/pitfalls would I have to doing a molybdenum disulfide or a polytetraflouroethylene dry film coating? Any suggestions?

Also, I've been playing around with the idea of adding a spiral groove to the ID of the bushing. Our system is lubricated with a propreitary degassed molybdenum grease.

Thanks!

RE: Bearings/Bushing, Dry Film Lubrication, Grooving....

What problem are you trying to solve?

 

Mike Halloran
Pembroke Pines, FL, USA

RE: Bearings/Bushing, Dry Film Lubrication, Grooving....

both coatings can be effective under mixed or boundary lubrication regime. if you are able to achieve fluid film lubrication the coatings will have no effect

RE: Bearings/Bushing, Dry Film Lubrication, Grooving....

As romke stated, once the fluid film is established the coating itself it not critical. I expect the coatings to influence performance during startups, shutdowns and dry-running spells. However, you should look into coating breakdown possibility within the range of operating temperatures.

 

RE: Bearings/Bushing, Dry Film Lubrication, Grooving....

What would be the purpose of the spiral groove?

RE: Bearings/Bushing, Dry Film Lubrication, Grooving....

(OP)
my (probably incorrect) concept on adding a spiral groove to the bushing is that if cut and installed in the correct orientation it could be carrying grease upwards to the ball race and other components. yes/no?

RE: Bearings/Bushing, Dry Film Lubrication, Grooving....

Hi.

Yes, in a "wet" boundary condition, neither MoS2 nor PTFE will serve you.  Both function as dry film lubricants.

What problem are you trying to solve?  Have you identified the mode of failure?  Friction, itself, is a system-dependent parameter and function of load, velocity, temperature, surface finish, counter-face, material hardness, etc.  

Grease tends to cold flow, displace under contact stress.  To try and direct the grease, through spiral, at the right rate seems implausible.  Not to mention depletion of lubricant.

You may want to see this link:  

<a href="http://www.industrialcoatingsworld.com/Low-Friction-Coatings/MoS2-Low-Friction-Coatings.html">MoS2 Low Friction Coatings</a>
 

William Gunnar
http://www.IndustrialCoatingsWorld.com
 

RE: Bearings/Bushing, Dry Film Lubrication, Grooving....

I think spiral grooves are sometimes used in bearings and bushings as "dirt grooves" to allow dirt particles to escape the clearance before doing too much damage.

RE: Bearings/Bushing, Dry Film Lubrication, Grooving....

grooves may be used in a bearing to direct the flow of oil or grease in a bearing. however, they should be very carefully designed in such a way that they do not constitute a path between a loaded and a unloaded zone of the bearing, otherwise you will not be able to get the hydrodynamical pressure buildup needed for proper lubrication.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources