Design Consideration for Selection of Bearings

[Rj87]

Hi,

I am just exploring my knowledge on bearing selection. Though I have some basic knowledge on bearing selections still I feel it would be good if I hear from experts so that I can improve my knowledge further. I'm looking for advise on following details.
1. Basic Design Considerations need to be considered for selecting bearings(This will vary for different types of bearings but still the over all consideration if any).
2. The calculations that needs to be performed when we use bearings in our design.
3. Any other additional info that will help anyone in selection of bearings.

Thanks in advance.



-----Knowledge is To Share, Not To Conserve-----

 

[JJPellin]

That is a very broad subject. Can you be more specific? Are you interested in rolling element bearings or hydro-dynamic bearings? Is there a particular equipment type that you would be working with?

The design or selection of bearings needs to consider a multitude of criteria: loads (thrust or radial, static or dynamic, steady state or transient), configuration (rotating shaft or stationary shaft, vertical shaft or horizontal shaft), environment (temperature extremes, contaminants), equipment criticality (general purpose / fully spared, special purpose / un-spared), rotational speed (maximum speed, minimum speed, single speed, multiple speed, variable speed, over-speed ,slow-roll), available lubrication systems (circulating lube oil), etc.

Many of these design considerations involve calculations. The bearing manufacturer will normally provide the design capabilities of their bearing. You would have to determine the conditions for your application to compare them to these design capabilities. If you don’t know enough to select the bearing yourself, then you would contact different bearing manufacturers and ask them for recommendations to fit your application.

I would recommend that you get a bearing manufacturer’s engineering handbook and read the relevant sections related to bearing selection. MRC and SKF have nice handbooks that I refer to often.


Johnny Pellin

 

[Tmoose]

"Basic Design Considerations ..... The calculations ....... Any other additional info that will help anyone in selection of bearings."

I don't think I see any mention of bearing fits in housings and on shaft or proper geometry of bearing seats. They are very important but aren't normally "calculated" as much as selected from manufacturer's tables with a thorough understanding of the importance of load direction, which race/ring/component rotates and more.

 

[geesamand]

Well to properly design a bearing within a machine, these things should be considered:
- How it will be installed
- What is it's L10 life, L10a life?
- How will it be lubricated? (Relubricated?)
- How will it be assembled?
- Will it be subjected to adverse conditions?
- What will the normal and extreme temperatures be?
- What fits should be used on the inner and outer race? (Generally the rotating side of a bearing must be prevented from shifting by way of a press fit or locknut)
- How much misalignment will it be subjected to?
- How will endplay/preload/thermal expansion be managed?
- Will the expected failure mode be acceptable for the machine? Will it be detectable? (Will it matter?)
- Is commercial availability important? (If so, how available is it?)

A few of these are calculations, most are not exactly.

The major bearing manufacturers have Engineering sections covering all of these things. You could do a lot worse than to study them.