Forced Vibration and Chatter in Horizontal Milling: An Investigation Using a Structural Model

This paper describes an investigation into the characteristics of, and interaction between, forced vibration and chatter in horizontal milling. The machine tool structure was simulated by a single-degree-of-freedom structural model.

The results show that forced vibration amplitudes: (1) vary with cutter speed in a series of resonance peaks; (2) are similar for plain and climb milling, but vary with orientation between the machining direction and the axis of vibration in a different way for the two processes; (3) increase approximately linearly with feed, except at low feeds; (4) pass through maxima and minima as depth of cut is increased.

The amplitudes and frequencies of chatter are distinct from, and depend on machining conditions differently from, those of forced vibration. Peak chatter amplitudes exceed those of forced vibration, but the latter can, under certain machining conditions, exceed chatter amplitudes. Forced vibration can thus be as much of a limitation as chatter when a good surface finish is required.

It was found that the discontinuous cutting of milling suppresses the onset of chatter relative to that for continuous cutting, for otherwise identical machining conditions. This is the reverse of previous contention.