Chatter frequencies of milling operations and their strengths
are analysed using the semi-discretization method. It is known
that milling processes, being parametrically excited systems,
are theoretically associated with infinitely many chatter
frequencies that are given as a base frequency plus an integer
multiplier of the tooth passing frequency (or the characteristic
frequency of the cutter) according to the Floquet theory .
The dominant vibration frequencies that are usually associated
with chatter frequencies are, however, hidden among the
infinitely many harmonics. In this paper, it is shown that the
amplitudes corresponding to the individual frequency harmonics
can be determined in a simple way by analysing the eigenvectors
of the Floquet transition matrix obtained by the semi-
discretization method without increasing the computational cost.
The method can be used to determine the dominant frequency
components that help in the identification of the interactions
between different modes and the spindle speed.