Heating up cast iron

[zoltan]

I'm going to be heating up an iron casting to install a bearing. It's the first time I'll be doing this. If I heat up the cast iron to 175*F is there any chance of it warping on me? My research says I'd need to heat it up a lot higher than that before it might start moving on me, but I figured I ask to make sure.

 

[MachineTom]

Heating up cast iron to 175°F will do nothing, not to the iron, nor to help putting in a bearing. Warping occurs when a small area is heated above 1200°, and then cools, like when brazing, an even heating below 1000 will not cause issues.

On large castings that are then extensively machined warping is potentially an issue. Its also common on steel that has been cold worked, then machined, it will move around after sitting awhile.

The expansion rate of iron stuff is around .000005" per inch per degree F. so a ! " bore will expand .000005 x100 or .00005 not much help.

 

[bazmak]

As a matter of interest Tom i recall the story of a bridge built where the 2 cantilever arches fell short by a no of inches.The steelwork was sealed with clay,filled with flamable liquid and lit.The steelwork heated/expanded and closed the gap.Truth or Myth ? Any comments

 

[tomrux]

Unless the liquid in question was IPN then I call Myth.
"As a matter of interest Tom i recall the story of a bridge built where the 2 cantilever arches fell short by a no of inches.The steelwork was sealed with clay,filled with flamable liquid and lit.The steelwork heated/expanded and closed the gap.Truth or Myth ? Any comments "
What you describe requires a fire in a vacuum. that fire would self extinguish in short order once it used up the small amount of oxygen available.

Tom R

 

[purpleknif]

Try liquid nitrogen to shrink the bearing .

 

[MachineTom]

Have you any idea what it cost to get Liquid Nitrogen, Store, Handle It. Second issue, he only has one bearing, What to do with the 30 gallons of the stuff, just blow it off. Be real.

Just put the part on the kitchen range warm it t 400° F and press in the bearing. There are products that are made to chill items, Liquid Nitrogen is -320°F Nothing in the store will get that cold, I have Freeze Spray made by Chemtronics, it does -60°, I bought it from MSC, but likely found other places. But whats still not much to shrink a bearing. Heat is so much easier.

 

[purpleknif]

Have you any idea what it cost to get Liquid Nitrogen, Store, Handle It. Second issue, he only has one bearing, What to do with the 30 gallons of the stuff, just blow it off. Be real.

Just put the part on the kitchen range warm it t 400° F and press in the bearing. There are products that are made to chill items, Liquid Nitrogen is -320°F Nothing in the store will get that cold, I have Freeze Spray made by Chemtronics, it does -60°, I bought it from MSC, but likely found other places. But whats still not much to shrink a bearing. Heat is so much easier.

I go the the welder's supply place with my igloo 6-pack cooler and they submerge my stuff for free. Actually Liquid nitrogen costs less than milk if you gotta buy it .

 

[Swifty]

What sort of press fit have you made? If the hole is bored the same size as the bearing, it will still be a tight fit, but you will be able to tap it in with a soft mallet. There is always loctite bearing retainer as well, good when the fit is a bit loose. I have used dry ice pellets in the past to freeze parts, but never bearings.

Paul.

 

[Wizard69]

I'm going to be heating up an iron casting to install a bearing.

What type of bearing?

As for the casting what happens depends upon the quality of the casting. You should be able to heat it up significantly without damage if there are no flaws. You should do this in an oven to attempt to heat it up as evenly as possible.

It's the first time I'll be doing this. If I heat up the cast iron to 175*F is there any chance of it warping on me? My research says I'd need to heat it up a lot higher than that before it might start moving on me, but I figured I ask to make sure.

Depending upon the bearing you could try shrinking it. Chilling the bearing will be just as useful as heating up the housing.

As for bearings themselves, Timken recommends heating a bearing to no more than 250°F.

Lastly why is this such a tight fit? Generally your outer races are not fitted extremely tight.

 

[velocette]

Hi
The spindle bearings on a X2 mill can be pulled into the housing with a collar and a washer with a length of threaded rod no need to heat up the housing.
Or can pressed in with a hydraulic press.
They can be tapped home with a hammer and a proper bearing drift.
Added a jpg file to help

Eric