To all,

How close to critical speed can be run without exicting resonance? Is it 10%?

Thanks in advance

Difficult to answer without knowing all modal properties. Damping controls amplitude levels at/near resonance.

I believe there are "guidelines" you can use depending on type of machine. Manufacturer should be able to help. As a minimum, acquire data as function of speed.

Take a look here:
http://www.eng-tips.com/viewthread.cfm?qid=160351

Interesting that some references require more % margin if operating just above critical speed than just below. Does anyone know why that is? Maybe they are expecting the stiffness may decrease over time?

Moejoe

The safe academic limits is 30%.
If less greater sensibility to unbalance up.

Ricardo Góz from Brazil