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Will dry ice ruin a bearing race?

Discussion in '80-Series Tech' started by racevws, Mar 20, 2017.

  1. racevws

    racevws

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    Totally random question, but if any of you guys are materials/ engineer guys, I would like to know if I cool my wheel bearing races in dry ice prior to dropping them in the hubs (as opposed to pounding them in), will it reduce their hardness after they come up to temperature? Also, will chilling them actually work?
     
  2. CDmpc

    CDmpc

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    this is a common work aid for interference fit parts- no worries. Liquid Nitrogen, Dry ice, freezer over night. Just be sure it is seated when it comes up to temp.
     
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  3. inkpot

    inkpot SILVER Star

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    Half ass cryo? No freezer burn AFAIK!
     
  4. the stig

    the stig

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    This. I build Jet Engines and we use dry ice on things like bearings and such all the time.
     
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  5. 4rings5cyls

    4rings5cyls

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    Sure hope not! Used it for most of the races when I redid the front axle. Definitely made things easier. Just wear gloves, if that isn't obvious.
     
  6. Notch

    Notch Supporting Vendor

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    Sounds like a solution looking for a problem but it won't hurt the metal. You'll need your hammer and driver/punch anyway to make sure they are seated all the way or you might be redoing the job when the bearing loosens up.
     
  7. LINUS

    LINUS Waiting for the Great Pumpkin

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    Nope to issues there, or the other way I use plenty - 110v induction bearing heater.

    The only trick to these people neglect to think of is ending on the right end of the AC wave cycle. You effectively make it a magnet every fraction of a second, so keeping a steel paperclip on a string is a good check. Wave it by the race, see if the magnet swings or not, bump the power until you get unmagnetized.

    We were told because a SKF bearing rep came out to help diagnose a situation we were smoking bearings in a compressor about the magetized bearings issue - worn shavings are quicker to wear a bearing than a non-mag'ed one, the fines stick where otherwise would float suspended in grease irrigation. --One of those times the real world beats 'internet smarts'.

    Common shop practice is to intentionally grease the bearing plenty (packed by jand like our axle bearing grease packers), watch for the 1st wisp of smoke (~22 sec on a axle sized bearing), grab the paperclip & bump the power.

    I'd think for most apps you want the bearing race hot to shrink fit it in a average cast housing, but whatever works for you - awesome.

    We use cold to expand a item, then heat to shrink -
    Frankly last time I used both was a 'government' job for a fella where 40's era CAT dozers use a slip fit, 2 piece powerdriven shaft you freeze the outer & heat the inner to slip fit to your appication. It's a static length in operation (runs the winch), but you have to adjust for the dozer application on setup. At least that was as I recall, I wasn't installing it, just adjusting length with him @ our jobsite.

    To get there took 2 full days in a chest freezer, covered in dry ice & me using a rosebud on a torch to get the opposite hot enough.

    Back to topic, induction bearing heaters are awesome if you do bearing work enough, I think you can rent them too, they are $$$.

    Here's similar to the shop one w/ diff size bearing hangers:

    Midi 3 3kW Speedfit Induction Heaters

    Here's a fancy one I'd love to have @ home (no idea the $$$$, proper size)
    Video explains operation too - worth a minute of your time:

    SKF High frequency portable induction heater TMBH 1
     
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  8. thatcabledude

    thatcabledude

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    ^cold to expand and heat to shrink?:confused:
     
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  9. the stig

    the stig

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    Pretty sure you've got things backwards. Cold=shrink, hot=expand
     
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  10. LINUS

    LINUS Waiting for the Great Pumpkin

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    Son-ofa-bish.

    Another case where I'm getting senile.

    I heat the bearing to go on the pump shaft, not in the housing.


    I fully had a 'senior moment' & own it.

    This is where I'm getting old & you all caught my old man butt. You caught 'The Tater'.

    Srsly, good catch.
     
    Last edited: Mar 20, 2017
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  11. LINUS

    LINUS Waiting for the Great Pumpkin

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    If you find yourself swapping ABS trigger rings on a birf, you now know a way.

    :cool:
     
  12. elripster

    elripster

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    You are good with cold. Be aware that it will be much more brittle so if you have to tap it in at that low temp use a soft drift (brass), not a hard steal one.

    Frank
     

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