The chip regeneration mechanism during chatter is influenced by vibrations
in three directions when milling cutters with ball end, bull nose, or incli
ned cutting edges are used. A three dimensional chatter stability is modele
d analytically in this article. The dynamic milling system is formulated as
a function of cutter geometry, the frequency response of the machine tool
structure at the cutting zone in three Cartesian directions, cutter engagem
ent conditions and material property. The dynamic milling system with nonli
nearities and periodic delayed differential equations is reduced to a three
dimensional linear stability problem by approximations based on the physic
s of milling. The chatter stability lobes are predicted in the frequency do
main using the proposed analytical solution, and verified experimentally in
milling a Titanium alloy with a face milling cutter having circular insert
s.