Bearing scheme for 30,000 RPM rotor: Guide lines

1. Radial deep groove ball bearings are commonly used in machineries
2.  Radial deep groove ball bearings contact angle is 8°. So it can take low axial load, compared to the radial load it can take. 
3. Radial deep groove ball bearings typically used with a separate thrust bearing.
4. Radial deep groove ball bearings  speeds are low as the balls are not in contact with both the races all the time. There is a clearance between outer race and balls.
5. Radial deep groove ball bearings  clearance between outer race and balls is given in the bearing number it self.
6. Fans, blowers, electric motors use Radial deep groove ball bearings 

 

1. Spindle bearing and angular contact ball bearings are the same. Two names of the same thing. So don't search radial spindle bearing.
2.  Spindle bearings have contact angle between 16-25°. So they can take higher axial load, in only one direction, compared to radial deep groove ball bearing. 
3. Spindle bearings need to be bought in pairs, to take load in both the directions, axially
4. Spindle bearing  are preloaded, so the balls are always in contact with both the races. So the speeds are higher compared to Radial deep groove ball bearings 
5.  cnc machine tool spindles and high speed rotors use angular contact ball bearing .

 

1.  If span between bearing is high and thermal expansion contraction are significant, one side bearing has to be fixed and other side has to be free for sliding. 
2. Fixed side bearing can be
1. Deep groove ball bearing
2. Matched pair or stack angular contact ball bearing
3. Double-row angular contact ball bearing
4. Self-aligning ball bearing
5. Cylindrical roller bearing with rib (NUP and NH types) 
3. Bearings which accommodate radial load only and whose inner and outer rings are separable are recommended as free side bearings.In general, if non-separable bearings are used on free side, clearance fit is provided between outer ring and housing to compensate for shaft movement through bearings. In some cases, clearance fit between shaft and inner ring is utilized.
4. Free side bearings can be:
1. Cylindrical roller bearing (NU and N types): Separable type
2. Needle roller bearing(NA type, etc.): Separable type
3. Deep groove ball bearing, clearance fit, Non-separable type
4. Matched pair angular contact ball bearing, Back-to-back arrangement, clearance fit, Non-separable type
5. Double-row angular contact ball bearing, clearance fit, Non-separable type

Optimum bearing arrangement for me is, back to back, angular contact type, example 13 in 

https://koyo.jtekt.co.jp/en/support/bearing-knowledge/4-0000.html

Shims are required on this type: "After mounting, the axial clearance is adjusted using nuts or shims. "

To avoid having shims, better to have a outer coaxial tube that with hold the outer race. This tube will transfer load from outer race to outer race axially. 

Clamp the outer coaxial non rotating tube on plummer blocks. Use lock nut with locking washer with a grove cut on the thread for the locking washer tab.

Similar arrangement is already there in page 31/70, https://www.cedengineering.com/userfiles/Ball%20Bearing%20Design%20and%20Applications%20R1.pdf

 

Timken clearly gives mounting arrangement: https://www.timken.com/resources/timken-angular-contact-ball-bearing-catalog_11193/

 

Similar arrangement with additional deep grove bearing on one side is also available as a standard product : https://in.misumi-ec.com/pdf/fa/2014/p1_985_001.pdf

 

For preloading details: see https://koyo.jtekt.co.jp/en/support/bearing-knowledge/11-2000.html

Decide between matched and universally matched bearings.