ISO1940 Standards and high RPM's

[dynaman]

Hi all

I'm currently balancing micro-turbine rotors using 2 plane balancing method. ISO1940 G2.5 requires a quality balance limit of 0.033mm.gram per bearing location in my case (100,000rpm), which I'm finding near impossible. Is ISO1940 limits a bit of an overkill? The best I can physically achieve is an order of magnitude higher (0.33mm.gram).

thanks

Dynaman.

 

[Tmoose]

**** What problems are you having ?

Are you verifying the residual unbalance in the tolerance planes, or the correction planes?

Please Describe your balance machine setup with words and pictures showing bearing configuration and rotor drive.
Are you balancing the rotor assembly, supporting it on the actual bearing journals, or is an impeller etc being mounted on a mandrel?


Also describe the method you are using to determine final residual imbalance . Direct Machine read out, trial weight "proving" , etc.
Do you have a copy of ISO 1940-1 and -2 ? The limitations of repeatability, and the complications of actually achieving finer grades (balancing in service bearings and more) are there for a reason, and are sometimes overlooked by the engineer dictating the notes for the drawing and purchase order.

 

[dynaman]

Hi Tmoose,

Yes I'm verifying residual unbalance in the tolerance planes. Its a home made setup with custom electronics and soft bearing rig. I've calibrated the setup using trial weights and then using influence coefficients to calculate residual unbalance as a direct readout. I have a copy of ISO1940-1, however i'm not sure what you are referring to regarding the last statement?

thanks

Dynaman