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Erbessd Instruments ISO Balancing Standards

ISO Balancing Standards embedded within DigivibeMX:

The two primary factors to determine permissible unbalance (also called the balancing tolerance) are the mass of the rotating part and the maximum operational speed.

Calculating a balancing tolerance based on these parameters is relatively simple. However, these calculated tolerances are for the journal planes, and must be transposed into the correction planes.

Based on experimental data, the potential for damage is proportional to the Balancing Quality Grade. Larger G numbers cause more structural stress.

The DigivibeMX software has a built-in balancing quality calculator for ISO and special custom standards.

Enter rotor mass, service speed and desired quality grade, and click CALCULATE. The correct unbalance tolerance will be calculated, and automatically transposed from journal planes into correction planes.

ISO 1940 is obsolete and has been replaced with ISO 21940-11, edition 2016-11-15. The DigivibeMX software Tolerance Calculator has been updated to this new ISO standard.

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 1.0 1.0 – Tape recorder and phonographs (gramophone) drives.
– Grinding-machine drives.
– Small electrical armatures with special requirements
G 0.4 0.4 Spinles, 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.


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