ISO Rotor Classifications
GO.4
Spindles, precision grinders, Gyroscopes.
G1
Small special purpose electrical rotors / drives.
G2.5
Gas / steam turbines, Turbo compressors, machine tool drives. Small
and special purpose electric rotors.
G6.3
Fans, Pump impellers, general electric rotos, centrifuge drums,
general machinery parts.
Balance Tolerances
ISO 1940 / 1
MCD (e
m) = G x 1000 = 9549 x G
2
n/ 60 n
Where:
G - Balance quality grade
n - Max rotor seryice speed
Uper (gmm) = e per.W
Uper (gmm) = 9549
x G
x W
n
Where:
G - Balance quality grade
W - Weight of Rotor in kilograms
n - Max rotor service speed in RPM
Symmetrical Rotors
Correction Plane L Correction Plane R
h1 hr
a b
d
Rules for Symmetrical Rotors
1. Correction Planes are between bearings.
2. Distance "b" is greater than 1/3 "d".
3. Correction plane are equidistant from the center of gravity.
Balance tolerance per Plane = Uper/2.
When correction planes are NOT equidistant from the center of gravity:
Uper Left = Uper ( hR/b )
Uper Right = Uper ( hL/b )
The Uper Left or Right should not be less than 30% or
more then 70% Uper. If they are then use the rules for
narrow plane rotors.
25
CG
