Hello all, today I tried an experiment that most of you may already know about, but it was knew to me so I thought I would share. It involved heating a bearing up to close to 100C / 212F but not over to install on a shaft. It uses a microwave oven. I did not want to try this with the good one in the kitchen. Yes I am married. We had an old microwave at work that was either getting thrown out, or donated to science to study what happens to a six month old stew that has been reheated 40 times. It could be used as an industrial coating, but that is a different story. The process involves wrapping the bearing in a damp rag or paper towel and giving it a couple of minutes on high. It is that easy. Now for the science part. The microwave oven heats the water molecules and the heat is rapidly conducted to the bearing. As water turns to steam at 100C / 212F the rag will only get to 100C / 212F. Therefore the bearing can’t get any hotter. Most of us have been told bad things happen when we put metal in a microwave. You may ask why not this time. Essentially the damp rag creates a Faraday’s cage around the bearing. The simplest explanation of this is the water conducts the radiation around the outside of the metal and not through the metal, therefor no arcing and sparking. If you leave it long enough, all of the water will turn to steam and then arcing may/will start. So if you find a $5 microwave on Gumtree you can quickly heat a bearing for ***embly. Steve from down under
Plain, old, light bulb placed on the bore. Or you could get really lucky, like I did years ago, and get a real bearing heater at an auction for $7.50, because nobody else knew what it was. Even the auctioneer had to ask me. Roger
The toaster oven works great, I’ve used one for years. Set heat at 250°F, never any higher it will affect the metallurgy of the bearing this according to all bearing manufacturers. As a millwright I’ve used these guidelines for years and it has always worked out. Use a 200°F and a 250°F temperature stick to check for accuracy. These are available at any professional welding supply store. Sent from my iPhone using The H.A.M.B. mobile app
I can't imagine steaming a bearing is very good for it. Moisture and hot steel is a recipe for iron-oxide.
You can buy bearing heaters but, they are not cheap. https://www.google.com/search?q=bea...7j0l6j69i60.3343j1j4&sourceid=chrome&ie=UTF-8
At the shop, when we put fork bottom races on forks, we put them in any old cup with water, and microwave the hell out of them. I wait until they are boiling furiously, then remove and push on quickly. Never any arcing, and the 40 year old shop microwave keeps on microwaving.
You can also put the shaft in the freezer for a while before ***embly. I do this for aluminum plugs in coolant channels in aluminum parts at work, (making scientific equipment) where I need a real tight fit, and would gall up both pieces trying to ***emble them without the heating and cooling. It might help with bearings too.
lots of good info. I had issues with bearing spacers on spindles. Put a bag of ice on the spindle and the bearing on the BBQ and checked with heat gun at 250--went on smoothly-done a few sets with no issues
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