Micropump Bearing Lubrication

Discussion in 'General Electronics Chat' started by joeyd999, Mar 28, 2014.

  1. joeyd999

    Thread Starter AAC Fanatic!

    Jun 6, 2011
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    I've been using this diaphragm micropump for many years in a few of my products:

    [​IMG]

    When it works, it works well. Lately, I've had problems with the ball bearing seizing up -- generally when the pump is exposed to cold temperatures.

    What I think is happening is that moisture is condensing on the bearing, causing oxidation and ultimately failure. A squirt of lubricant makes the pump work perfect again -- regardless of temperature (i.e. expansion and/or contraction is not causing the problem).

    So I want to lubricate the bearing before installing the pump. I need a low viscosity lubricant that will resist moisture long term, and not collect dust/dirt. This is not a field-serviceable item, so I need the lubricant to last. It also needs to be compatible with the plastic (ABS) housing and rubber diaphram.

    Any ideas?
     
  2. MaxHeadRoom

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    Jul 18, 2013
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    What you really need is a sealed bearing, especially if you want it non-servicable item, as any bearing exposed is going to attract dust etc.
    I have used the Silicone greaseless lubes before, but they will not last or endure as long as a sealed bearing.
    It may be worth looking into replacing them with sealed versions.
    Max.
     
  3. joeyd999

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    For various reasons, replacement is not an option. I must use the pumps I have. I am currently experimenting with Silicone, PTFE, and lithium based lubricants. I am also trying the old stand by, 3-in-1 oil.
     
  4. MaxHeadRoom

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    I actually meant replace the bearings not the pumps, if this was misinterpreted.
    Usually the price for small sealed bearing for those pumps should be minimal.
    Max.
     
  5. joeyd999

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    It's very difficult to remove and replace the bearing without destroying the pump (been there, done that). And the pumps are relatively expensive.

    At this point, I am hoping the proper lubricant can at least mitigate a good portion of the failures I am seeing.
     
  6. strantor

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    I have seen non-serviceable gear boxes come full of graphite. Maybe that would work.
     
  7. joeyd999

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    The issue, I believe, is condensing moisture causing oxidation of the bearing. Load/wear is not a problem. I need to coat the balls with something to prevent exposure. I don't think graphite will do that.
     
  8. PackratKing

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    Don't do it

    Three - in - one will destroy your motors.. It is akin to vegetable oil. It turns to glue over time, and then to concrete...
     
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  9. crutschow

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    You might try contacting a lubricating oil manufacturer with you problem. They should be able to suggest the best product for that.
     
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  10. #12

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    For light duty bearings, Hoppe's Gun oil does not have stuff that turns gummy. Still, it makes no claim to keep water out.
     
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  11. GetDeviceInfo

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    Jun 7, 2009
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    Cold will stiffen the diaphragm, substantially increasing the load. Don' discount that. Moisture needs to be excluded. A barrier that also acts as a lubricant reserve works best. A felt washer held appropriately could serve.
     
  12. Metalmann

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  13. shortbus

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  14. joeyd999

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    Thanks for jogging my memory, #12. I use Birchwood Casey Synthetic PTFE lube for my Glock. It's light weight, doesn't dry, and is tested for high temp/high humidity environments...

    I've begun testing it today...we'll see how it goes.
     
  15. atferrari

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    What is "light duty" here? No heavy mechanical load, low duty cycle or both?

    I learnt that in actuators both seem to go hand in hand (but no sure).
     
  16. joeyd999

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    Thanks! I also learned that the viscosity of lithium based lubricant increases dramatically at low temperatures.

    So far, the synthe PTFE gun oil is working best.
     
  17. PackratKing

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    I grade various greases for film camera, long telephoto, and zoom-lens helical threads, with a flame test...

    Place a dab on a microscope slide, and apply a flame from a distance and move gradually closer... time how long it takes for the base oil to commence to run down the slide... Lenses never really get that hot on a summer day, BUT..... if that base oil gets into your aperture mechanism via capillary action, you will get sporadic gross overexposures... or if it migrates into the lens groups... which often have fragile coatings easily ruined by the oil...
     
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