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critical speed-bearings

critical speed-bearings

critical speed-bearings

(OP)

 How to calculate critical speed of bearings and gears?

RE: critical speed-bearings

critical speed [~/min] depends on outside diameter (D) of bearing

D<30:  n = {(3 * A) / (D + 30)}* k   or,
D_>30: n = {A / (D-10)} * k

A (grease lubrication)
    A = 500000; in case of radial ball bearing
    A = 360000; in case of double row angular ball bearing
    A = 320000; in case of double row ball bearing
    A = 250000; in case of double row spherical roller
    A = 220000; in case of spherical roller bearing
    A = 140000; in case of axial groove bearing

Oil lubrication = A * 1.25

k = 1 if F radial or F axial is smaller than 0.1*C and 0.5<k<1 if 0.4< (Fa/Fr) <100

RE: critical speed-bearings

I forgot,

Using ceramic balls (Si3N4) makes the critical speed of an deep groove ball bearing 30% higher

RE: critical speed-bearings

Bearing cage construction and material will have an effect here, along with the bearings precision grade, ie ABEC 5, 7, 9 HG etc... You would have to consult the appropriate manufactures catalogue in order to gain the correct multipliers. GMN used to do an excellent example in their catalogues.

AHR International Ltd
http://www.ahrinternational.com

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