34) Why does the mechanical quality factor Qm vary among good and identical sonotrodes?

FAQ: If we find discrepancies in Qm value in the same lot of sonotrodes, showing the same dimensions and frequency, can I attribute to the material the cause for the Qm value to differ? Is it a problem?

The sonotrodes Qm variation you report may has to do with the joint surface finishing and mounting torque, not with material damping variation. Whether it is a problem, will depend on the standard deviation and average. In contrast to frequency strict tolerance, Qm may varies much more, ±20 % is usual and not a problem if the average is high and there is no value below the minimum Qm for sonotrodes (1000).

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