The use of high speed or trochoidal tool paths, that is, high axial depths of cut combined with low radial widths of cut or stepovers, typically 10% or so. When users experience chatter they keep reducing the stepovers from 10% down until they do not hear chatter. We have a trochoidal milling setting in MillMax.
With very small stepovers, the cutting edges spend less and less time inside the cutting area. Hence, the cutting forces lose their sinusoidal shape and become similar to impacts (like grinding), which excite the modes of the system. Chatter is not an issue but surface finish may be. The SLE and CDD gages may be of use in these cases.