Table of Contents

Chatter, and What the Simulation Does About It

Chatter is self-excited vibration between cutter and workpiece, and it is the one failure mode that a purely geometric look at the toolpath cannot see. HiNC does not predict chatter directly. What it does instead is give the cut a force ceiling that keeps it out of the regime where chatter starts, which covers the cutter side and leaves two other cases to be handled by the operator.

Cutter Chatter — Handled by a Force Ceiling

Cutter chatter does not begin while the cutting force stays below a threshold. That threshold is a property of the machine, not of the program: a well-maintained machine tolerates a higher force before it chatters, and the same NC on a worn one will chatter earlier.

So the lever is the optimizer's preferred cutting force (OptPreferedForce_N). Optimizing to a preferred force holds the cut under a ceiling for its whole length instead of only at the peaks, and if a particular machine still chatters, the answer is a lower preferred force rather than a different toolpath. The value that works is found once per machine and reused.

Workpiece Chatter — Not Estimated

Workpiece chatter is not estimated. A thin, tall or poorly supported workpiece can vibrate at forces the cutter itself tolerates comfortably, and nothing in the simulation reports it. Where the part is the flexible member, the force ceiling that protects the cutter is not the ceiling that protects the surface.

Fixed-Frequency Vibration — Not the Program's Fault

Fixed-frequency vibration comes from the machine's own condition — bearings, drives, structure — and is independent of the toolpath. No NC change removes it, and re-optimizing will not help. The practical avoidance is a spindle speed that does not coincide with the machine's harmonic frequencies.

Strain Hardening — Why It Is Not Modelled

A related question that comes up in the same conversation: milling's depth of cut is far greater than the strain-hardened layer left by the previous pass, so the hardened material is a small fraction of what each tooth removes. The effect on the process is minimal, and the simulation does not model it.

See Also