Oil ring Vs Oil Bath

[1ton]

Hi

Just would like to know what would be the reason to go for oil ring lubricated bearing against oil bath lubricated.

Thanks

 

[electricpete]

One factor - for lower speed rolling bearing machiens, it may be practical to partially submerge the rolling element.. .for example level at 1/4 - 1/2 of the lowest ball on horizontal machine. For 3600 rpm machines, submering 1/4 of the lowest ball would probably cause excess heating. And if you tried to only submerge 1/8 of the lowest ball you would be walking a tightrope on maintaining oil level... so the oil ring (or some type of flinger device) is needed instead of partial-submergence in oil bath for higher speed rolling bearing machines

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[1ton]

Thanks electricpete for the infomation. Would you say rule of tumb any thing in exceed 3600rpm we would go for oil lubricated ring.

Is there a way to calculate this out or is it base on experience ?
Thanks again

 

[GPRnD]

The rule of thumb we use is that 2 pole machines generally should have oil ring as opposed to oil bath.

This is not to say you cannot have a successful oil bath design running at 3000 RPM (I've designed several). However it becomes very critical to control the oil bath level. At 3600 RPM, I'd always recommend oil ring because of the reduced churning and heat generation.

However the caveat to the above is that it depends on the size of bearings you are using. Very small bearings will be fine with an oil bath even at high speeds.

The other issue with oil rings is that they can be tricky to design and execute properly. We have spent many hours testing and improving our designs. In particular the material of the oil ring and how it is guided are very important.

If you post details of the bearing size and application I can be a bit more specific.

 

[1ton]

Thanks bradshsi

I don't have bearing size, I am just trying to specify if oil ring is required over oil bath. Since speed is a factor. And as a rule of tumb rpm over 3600. How about power (kW) or shaft power which translate into bearing size ? What do you think, a typical power rating of a shaft to go for oil ring ?

Thanks again