ball bearing question

[autoguru]

Got a question on ball bearings. It seems there are still sliding friction involved in a ball bearing, even if we assume the ball rollers have a rolling friction of zero (perfect rolling with slipping).

I think there must be some kind of friction between the balls (or needles rollers) and the its axis that holds it in place. The balls are "held into" specific positions in a bearing, whether it be a axis, some kind of groove, or holder.

When the ball rotates, there must be sliding friction between the ball and the holder.

Is that even right?
Thanks

 

[ccw]

Hi autoguru

You are correct. For some applications the friction is so small that the bearing will operate OK without any lubrication.

For Conrad race ball bearings it is practically rolling contact only at the main load bearing points of contact. For angular contact race ball bearings there is some minor rubbing.

For needle bearings there is some rubbing at the ends and between rollers, but the loads are very small compared to the main bearing loads.

 

[Barry1961]

Of course if you have a sealed bearing you have friction from the seal. You also have to "stir" the lubricant which be significant depending on temp, lube type and speed.

Barry1961

 

[autoguru]

Does anyone know the approx. cost of a needle bearing? diameter about 1cm.

Thanks

 

[MadMango]

Need more info...
Open, sealed, doubled-sealed? 1cm ID or OD? Load rating?

I would say they range from $2.50-$12.00USD depending on vendor, and annual consumption.

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[autoguru]

open,
1cm ID.
load 1000 lb
makes 1 million annually.

I guess I want the approx. manufacturing cost, rather than the vending price.

Thanks

 

[MikeHalloran]

That's a very, very large load for a bearing of that size.



Mike Halloran
Pembroke Pines, FL, USA

 

[autoguru]

Fine, how about 200 lb.

Just need a general idea of the manufacturing cost of such a bearing.
Thanks

 

[MikeHalloran]

At FoMoCo, four decades ago, we made our own u-joints, and bought the needles outside, for well under a penny apiece.

Prices are up more than tenfold today, so it might cost you $2 for a set of needles and $.50 for a shell, if you need one. Or not; that's a really rough guess.

For a million bearings a year, you can certainly get the attention of any bearing salesman; contact some and ask for catalogs, CDs, whatever.

To get a real quote, you will need to give a more precise estimate of the nature of the load, the imprecision you can tolerate, the packaging and preparation you need, and more details about the housing and the shaft. The catalogs should explain all of that.









Mike Halloran
Pembroke Pines, FL, USA

 

[ischgl99]

Are you looking to build them yourself? If not then the manufacturing cost is useless to you. If you want a cost, the only one that matters is what someone will sell it to you for.

The cost will be dependant on what you really need, first you need to settle on your actual load, then you can get a better idea of the cost. INA manufactures millions of bearings in that size each year, give them a call and your specifications and you will get an actual cost instead of a guess.