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Old 07-19-18, 09:51 AM
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Originally Posted by nfmisso View Post
The best ball bearing steel is 52100; it is very magnetic, and requires corrosion protection.

440C is a stainless steel, nearly as good a bearing material as 52100, it is magnetic, easy to pick up with a strong magnet. Better at not rusting than 52100, but not very good compared to other stainless steels.

Non-magnetic stainless steels do not make very good bearing balls, avoid.
OK, before I get more confused, when we say a certain ball bearing is "magnetic", don't we mean that said ball bearing is composed of "ferromagnetic" material, for example steel, but may not necessarily be "magnetized"? I used to use a magnet to position new balls into their corresponding cups until I noticed the new balls were becoming magnetized by my doing so and thus sticking to each other. Hopefully only temporarily, but still I know of a great deal of lubricated machinery having a magnet placed inside in a strategic location, usually a drain plug, to attract and hold any ferromagnetic grit or filings so as to keep it all out of the bearings as much as possible. If magnetizing new ball bearings might attract steel grit to them I thought it prudent not to. If just they lose their magnetic fields guickly, maybe no big deal. I still use the magnet to quickly pull out old balls for disposal though.
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