Self excited vibrations in external cylindrical plunge grinding are primarily caused by directional coupling and secondarely by regenerative effects on the surfaces of the workpiece and the grinding wheel. Assuming that directional coupling and workpiece regenerative effects occur at the same time a dynamic material removal rate can be computed, which can approximately be assumed to be proportional to the dynamic cutting force. According to this investigation it can be shown that the workpiece regenerative effect as a causing mechanism of vibration reaches into a much higher frequency range as recently assumed.