Is liquid nitrogen safe?

[gary808]

Is it safe to shrink bearing races in liquid nitrogen?
Plan on taking them down in a freezer then the nitrogen to fit them. These are about 8" diameter races.

Any thoughts?

 

[Welder Dave]

It's common but you have to take precautions like wearing suitable gloves and protective wear. Liquid Nitrogen is about -195C but is used in cooking and other applications as well. No need to put your races in a freezer first. You need a dewar to contain the liquid nitrogen. Mining companies use it to freeze large pins. Depending how much you need to shrink the racers, dry ice is another option and easier to transport. You usually get it in pellets in a burlap type bag and can carry it in a cooler. It's about -70C. Both can cause asphyxiation so make sure you have adequate ventilation. A place I worked at sold it and they said to keep the windows of your car open when transporting.

 

[92U 3406]

As long as you're in a ventilated area and wear proper PPE its fairly safe. Tie a piece of wire around the races so you're not reaching into the liquid nitrogen to pull them out once they're frozen.

 

[gary808]

Okay thanks for the info. Im not to worried about my safety. I've handled it for shrink fitting pins and bushings. Just curious if bearing races would be ok.
I have used dry ice before on bearing races but the temp dosent give you much time to get it seated before it expands.
Thanks for the info.

 

[Cmark]

You need to be mindful that as the bearing comes back up ambient temperature, water will condense on it. You will have to dry and oil it immediately to stop it flash rusting.

 

[gary808]

You need to be mindful that as the bearing comes back up ambient temperature, water will condense on it. You will have to dry and oil it immediately to stop it flash rusting.

Thanks for the tip, I'll make sure we clean ans oil them.

 

[redneckracin]

I've done 4" press fit bushings that were .003 or .005 oversized with dry ice and it worked great, just make sure if its a vertical bore that you have a way to hold it where you want it while it expands.

 

[Old Magnet]

Remember that metal gets brittle at extremely low temperatures. I'd limit use to the dry ice.

 

[gary808]

Remember that metal gets brittle at extremely low temperatures. I'd limit use to the dry ice.

Thats what's been bothering me. I don't want to have these races crack.
We will probably just stick to dry ice.

 

[td25c]

Never did use liquid nitrogen for bearing installation but imagine it would cool a Barley Soda down quick .

De burr & clean up the bore good and we just use old school race driver punch on everything .
https://store.snapon.com/Oval-BEaRing-Race-Punches-20-Oval-Bearing-Race-Punch-P643668.aspx

Working on dozer final drives gary808 ?

Only time I was ever around liquid nitrogen was when we was artificially inseminating cattle .

It kept the " Bull juice " cool until the rite time .
http://www.selectsires.com/programs...andlingFrozenSemenStraws.pdf?version=20170404

My God........... I showed the Bull how to do this how many times ?? Hard to find good help anymore .

LOL !

 

[Cmark]

As long as you use workmanlike methods for installing, ie. correct pullers and drivers you shouldn't have any problems with cracking. I never have.
https://www.heavyequipmentforums.com/attachments/35-jpg.114145/
https://www.heavyequipmentforums.com/attachments/36-jpg.114146/

 

[RayF]

I've been using liquid nitrogen for around 30 years to install bearings,probably thousands of them. I have broken one bearing. It got stuck and grabbed and we tried to flog it in with a 14 lb hammer. The flange on the bearing broke off.
A handy rule of thumb for nitrogen is
Steel bearing shrink .002 per inch of diameter. (4 inch bearing comes down about 8 thou)
Bronze bearings come down 4 thou per inch of diameter.

 

[hvy 1ton]

Only time I was ever around liquid nitrogen was when we was artificially inseminating cattle .

It kept the " Bull juice " cool until the rite time .
http://www.selectsires.com/programs...andlingFrozenSemenStraws.pdf?version=20170404

My God........... I showed the Bull how to do this how many times ?? Hard to find good help anymore .

LOL !

Funny you mention that TD, I have some family that had a big part in popularizing AI. My dad swears up and down they used an airstream to haul around the good stuff. Couldn't help but think of the mess if somebody hit that trailer.

 

[td25c]

That's pretty cool hvy 1ton ! The Old Man was big into AI as well .

He could remember doing it when he was a kid back in the late 1950's . Nothing like today but was a start .

 

[gary808]

Well we got all the bearings seated today. Couldn't get Ln because we have ro provide our own dewar. We ended up getting 10 lbs of dry ice and mixing in a gallon of acetone.
We got the biggest pot we could find and boiled the expanding parts in oil to 250 and froze the shrink parts.
Worked our really well, everything just dropped together.

 

[gary808]

The bevel gear shaft was to large for the cooler so we did one side at a time.

We cleaned everything with decently hot oil after to remove condensation.

 

[gary808]

Btw the bearings and rads are for a d9h bevel gear shaft and housings and the transmission pinion bearings.

 

[gary808]

Never did use liquid nitrogen for bearing installation but imagine it would cool a Barley Soda down quick .

De burr & clean up the bore good and we just use old school race driver punch on everything .
https://store.snapon.com/Oval-BEaRing-Race-Punches-20-Oval-Bearing-Race-Punch-P643668.aspx

Working on dozer final drives gary808 ?

Only time I was ever around liquid nitrogen was when we was artificially inseminating cattle .

It kept the " Bull juice " cool until the rite time .
http://www.selectsires.com/programs...andlingFrozenSemenStraws.pdf?version=20170404

My God........... I showed the Bull how to do this how many times ?? Hard to find good help anymore .

LOL !

Bevel gear shaft and bearing here. We haven't got the the finals yet but I'm sure we're eventually headed there :/.
We thought about pressing them in but it was really tough removing the old ones. Even after they were partially split and the housings flash heated. The book called for heat and cooling so we figured it would be easiest. They all ended up just dropping in perfectly I didn't even have to pick up my trusty sledge.
And boy does that sound like a job haha sounded like a job for Mike row to do a show on!

 

[Welder Dave]

I don't know if putting hot oil on a very cold part is a good idea. Once the part thaws out would be better.

 

[gary808]

I don't know if putting hot oil on a very cold part is a good idea. Once the part thaws out would be better.

We thought the same thing so we gave everything about a hour to get to room temp then cleaned it with the oil. The oil was probably 120 to 140. You could touch it but not keep contact.