AbstractAn analyzer has been developed for the purpose of tracing and visualizing the time dependent variation of chatter in terms of the frequency and the magnitude, and of determining the spindle speed for real-time on-line chatter suppression.The system processes the vibration signal detected either by accelerometer or microphone and first screens out whether the signal should be analyzed or not, discarding signal during non-cutting period and/or vibration-free cutting. The signal accepted by the first screening, is next differentiated whether the vibration is chatter or not.The system then estimates from the frequency of the chatter identified, the natural frequency of the structural system causing the chatter as well as the spindle speed preferred for elimination of the chatter.Experimental evidences are presented demonstrating the way chatter frequency changes versus time in high speed milling and the effectiveness of the real-time on-line control of the spindle speed.