Bearing Life Calculations in an electrical motor

Case Description

Electrical Motor with two bearings which drives a pump horizontally

Motor Rotor Weight : 1160 kg - equally supported by two bearings ( no thrust load expected to come to motor side )

Shaft Diameter = 60 mm

Speed = 3000 rpm

Preference : Pregreased bearings

Expected Bearing Temperature : Close to 80 deg C

Required Bearing Life : 30.000 hrs ( 3-4 years life )

Radial Load on each bearing ( 580 KG ) only from shaft weight = 5.7 kN

Deep Groove Ball Bearings with shaft diameter 60 mm :

6012 - ZZ ---- Dynamic Load Rating C = 30.7 kN C/P = 5.4

6212 - 2Z ---- Dynamic Load Rating C = 55.3 kN C/P = 9.7

6312 - 2Z ---- Dynamic Load Rating C = 85.2 kN C/P = 15

Basic Load Rating

Seems 6312 is a good starting choice here but Grease filling and contamination factors should be considered not only the bearing basic life calculations are enough...

In the next article will continue considering other factors.