Hello everybody
1. when do we need high speed balance exactly in industry?
2. is it possible a balanced rotor in 40000 rpm (above second critical speed), show unbalance in 3000 rpm balance machine؟
2 you can't reliably balance for high speed operation (defined as more than 1/2 the first critical, for the sake of argument) in a low speed machine. The reason is that a low speed machine assumes that the shaft is rigid, which of course it won't be above 2nd critical.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376