Bearing (surface) pressure versus load rating

[Mech_LS24]

TL;DR

What is the difference of bearing surface pressure and load rating? Which should been taken during designing with bearings

Hi,

From suppliers of bearings, some of them specify the maximum bearing (surface) pressure or the maximum load rating (static or dynamic). What's the difference between this two? And which is most commonly used during selecting and calculating bearings in a mechanical design?

Thanks in advance,

 

[FEAnalyst]

When selecting bearings we generally use load rating $C$. You can find the details about bearing selection and calculation procedure for different types of bearings for example in „Shigley’s Mechanical Engineering Design”.

 

[Mech_LS24]

Thank you @FEAnalyst .

Are you familiar with bearing pressure and where it's used for ?

 

[Baluncore]

From suppliers of bearings, some of them specify the maximum bearing (surface) pressure or the maximum load rating (static or dynamic). What's the difference between this two?

Are you referring here to hydrostatic or oil wedge theory, or to rolling contact bearings?

 

[Mech_LS24]

Are you referring here to hydrostatic or oil wedge theory, or to rolling contact bearings?

Sorry for the misunderstanding @Baluncore. I was referring here to a sleeve bearing (Sleeve bearing example). You can see here the surface pressure for this part:

 

[Mech_LS24]

What is the difference between this surface pressure or the C-value which is commonly given for example with SKF bearings?

 

[Baluncore]

Google SKF C rating and you get;
"The C value is defined as: the bearing load that will result in an ISO 281 basic rating life of 1 000 000 revolutions. It is assumed that the load is constant in magnitude and direction and is radial for radial bearings and axial, centrically acting, for thrust bearings".

I think you must take what a manufacturer gives you, and apply it as best you can.
Comparing different standards will be more difficult than applying the one standard provided.

 

[Mech_LS24]

Thank you for the explanation :).

 

[Baluncore]

The iglide® M250 material is certainly interesting.
It has similar properties to some PEEK-PTFE composites.

 

[Mech_LS24]

What makes it interesting? Compared to the others, the static surface pressure looks quite terrible. On the other hand, the surface pressure is almost constant while increasing the temperature up to 150 degrees.

Source: Iglide M250