Suppression of regenerative chatter via impedance modulation

A new technique for the suppression of machine tool chatter in turning based on modulation of the system impedance is analyzed. The modulation frequency is selected as half the spindle frequency Using the method of harmonic balance and a numerical root finding scheme on the transcendental characteristic equation, stability diagrams are computed for a variety of modulation amplitudes. The stability boundaries are verified by using the Nyquist stability criterion and growth exponents computed from transient simulations of the vibratory response. It is shown in this way that the impedance modulation technique successfully scrambles the regenerative process that leads to chatter and widens the stability region (by increasing the maximum allowed cutting depth), particularly for low values of the spindle speed.