Motor rating and bearing selection. 1

[N.Kim]

I am currently researching on a new power utility device and encountered a few challenges where my knowledge falls short. Let me highlight them as follows:
Data:
- A set of 30 discs of inner diameter 0.96m thickness 0.03m outer diameter 1.2m thickness 0.1m.
-Each disc has an approximate mass of 120kg.
-From point 1; the disc are not hollow.
-Surface roughness is 0.2 microns.
-Target constant speed is 3000RPM.
-Acceleration is not an issue as reaching and maintaining that speed is what matters.(Acceleration can take several hours depending on the most energy efficient way)
-The discs are spinning freely.( In air or preferably vacuum )
-The discs arranged vertically and are coaxial.
-The discs are equidistant from each other at 0.12m

My problem is:
- Which bearing is suited to handle such a mass at such high speeds.
-The bearing should have as minimal frictional and drag losses as possible.
-What is the best rough estimation of motor size required to spin and maintain such mass at given speeds; considering that a larger motor than necessary is undesirable due to high energy consumption.
-What gear ratios are needed to pull that off.

My biggest concern is energy consumption please bear in mind that when looking into my query.

 

[electricpete]

it is a high inertia, low torque load for the motor. As such, I think the starting considerations will dictate motor selection.

Assuming squirrel cage induction motor, I think you can use a lot smaller motor if you include a vfd or possibly reduced voltage start. otherwise you'll need a larger motor to accelerate the inertia in DOL start without damaging / tripping the motor.

maybe other options besides squirrel cage induction motor can be considered,

=====================================
(2B)+(2B)' ?

 

[drawoh]

N.Kim,

Look into pre-loaded spindle bearings. Theses generally are rated for 30000rpm.

--
JHG