This article will show you how to use heat to remove bearings and other steel press fittings from aluminum housings.1
Aluminum-steel interfaces only
This trick only serves to burn your fingers if you try it with anything other than soft metal (aluminum) / hard metal (steel) interfaces.
Tools needed
- Hot Pads (no really. This is gonna get pretty hot.)
- Oven capable of 300°F
Pre-Planning
In about 15 minutes you are going to have a really hot aluminum thing that you are going to need to press something out of. If you touch it with your bare hand or drop it on yourself, you could be seriously burned. Aluminum dissipates heat quickly which means that all your trouble with the oven will be waisted if you can't quickly get to work.
If your object is very large, set up a mount of some sort in order to hold onto your object while you remove the bearing. In this case, I will use the tire in which my wheel half was previously mounted. The rubber of the tire should be able to take the heat and firmly hold my wheel half while I press the bearing out.
Also, make sure you prepare a place for your object to cool. It could take 20-30 minutes for your object to be safe to touch again, depending on how massive it is. A cool burner on the top of the stove is quite appropriate in most cases.
Preheat that Oven to 300°F
Before putting your object in the oven, preheat it to 300°F. You want to preheat in order to make sure that you are actually getting your aluminum to the right temp for the trick to work and to ensure that you don't end up letting your object heat for too long. This trick is commonly used to press out bearings which, at 300°F for long enough, will release all of their lubrication into the bottom of your oven or even have their seals melted.
In my case, I don't care much for the bearing I am removing since it has gotten very gritty and I am removing it in order to replace it anyway.
Throw your object in there
15 minutes should be plenty long for your aluminum to heat to the correct temperature. Make sure to have a hot pad or two ready to remove it once it is ready.
Take it out and setup
You are going to have to move fast. but there is no need to run. Use the hot pads to remove your item form the oven and prepare to press the steel out.
In my case, I have the wheel in the tire with the nut driver ready to push on the bearing. It only took a couple of light taps to get it out.
Cool down
Once you have pressed out the steel piece, find somewhere safe to let your item cool. Don't forget that whatever you pressed out is hot, too!
I just used the burner on top of the over (without turning it on) to let my wheel cool.