Balancing is a specialist field and some basic insight into the subject can help improve product design, product quality, and production throughput.

Need to work out a balance tolerance?

Universal Balancing’s Tolerance Calculator utilizes the ISO Balance Quality Grade G and combines it with part specific information to calculate a balance tolerance.

Tolerance Calculator


ISO Balance Quality G Grade

ISO Balance Quality G Grades are used to calculate balance tolerances in conjunction with the rotor weight and service speed (RPM).

Balance Grade G EW 1] 2] MM/s Rotor Types - General Examples
G 40 40

- Car wheels, wheel rims, wheel sets, drive shafts.

- Crankshaft-drives of elastically mounted fast four-cycle engines (gasoline or diesel) with six or more cylinders4).

- Crankshaft-drives for engines of cars, trucks and locomotives.

G 16 16

- Drive Shafts (propeller shafts, cardanshafts with special req

- Parts of crushing machinery. 

- Parts of agricultural machinery. 

- Individual components of engines (gasoline or diesel) for cars, trucks and locomotives. 

- Crankshaft-drives of engines with six or more cylinders under special requirements.

G 6,3 6,3

- Parts or process plant machines.

- Marine main turbine gears (merchant service).

- Centrifugal drums.

- Fans

- Assembled aircraft gas turbine rotors.

- Fly wheels.

- Pump impellers.

- Machine-tool and general machinery parts.

- Normal electrical armatures.

- Individual components of engines under special requirements.

G 2,5 2,5

- Gas and steam turbines, including marine turbines (merchant service).

- Rigid turbo-generator rotors.

- Rotors.

- Turbo-compressors.

- Machine-tool drives.

- Medium and large electrical armatures with special requirements.

- Small electrical armatures.

- Turbine-driven pumps.

G 1 1

- Tape recorder and phonographs (gramophone) drives.

- Grinding-machine drives.

- Small electrical armatures with special requirements

G 0,4 0,4

Spindles, disks and armatures of precision grinders.

- Gyroscopes.

1] w=2xn / 60-N / 0, if n is measured in revolutions per minute and w in radians per second. To simplify: Tolerance = Component Weight [kg] x Quality Grade x 9549 / Operational Speed [RPM]

2] In general, for rigid rotors with two correction planes, one-half of the recommended residual unbalance is to be taken for each plane.