Sono state stabilite delle classi di qualità di bilanciamento G che consentono di classificare i requisiti del livello di squilibrio residuo ammissibile per il tipo di rotore che ne garantisce il funzionamento soddisfacente. Le classi sono presentate nella tabella, dove il numero crescente indica uno standard meno restrittivo. Il numero rappresenta la velocità di vibrazione massima consentita di un pezzo in rotazione.
For justified reasons, it is possible to graduate the allowable rotor vibrations speed more precisely.
To calculate the unbalance value in [gmm] depending on the grade G, the following formula is used:
Uper = 9549 · G · m/n
where:
Uper – allowable rotor unbalance [gmm]
m – rotor weight [kg]
n – maximum rotor service speed [r/min]
In the case of balancing rotor in two planes, the above value is the total value for the rotor. Due to its geometry, it must be properly divided into planes 1 and 2.
Grado G [mm/s] | Esempi di rotori di bilanciamento |
4000 | Crankshaft drives for large, slow marine diesel engines (piston speed below 9 m/s), inherently unbalanced |
1600 | Trasmissioni ad albero a gomito per grandi motori marini diesel lenti (velocità del pistone inferiore a 9 m/s), intrinsecamente bilanciate |
630 | Trasmissioni ad albero a gomiti, intrinsecamente sbilanciate, montate elasticamente |
250 | Trasmissioni ad albero a gomiti, intrinsecamente sbilanciate, montate elasticamente |
100 | Motori alternativi completi per auto, camion e locomotive |
40 | Cars: wheels, wheel rims, wheel sets, drive shafts Crankshaft drives, inherently balanced, elastically mounted |
16 | Agricultural machinery Crankshaft drives, inherently balanced, rigidly mounted Crushing machines Drive shafts (cardan shafts, propeller shafts) |
6,3 | Aircraft gas turbines Centrifuges (separators, decanters) Electric motors and generators (of at least 80 mm shaft height), of maximum rated speeds up to 950 r/min Electric motors of shaft heights smaller than 80 mm Fans Gears Machinery, general Machine tools Paper machines Process plant machines Pumps Turbo chargers Water turbines |
2,5 | Compressors Computer drives Electric motors and generators (of at least 80 mm shaft height), of maximum rated speeds above 950 r/min Gas turbines and steam turbines Machine-tool drives Textile machines |
1 | Audio and video drives Grinding machine drives |
0,4 | Gyroscopes Spindles and drives of high-precision systems |