Current methods for estimating chatter stability limits for milling do not consider the influence of the helix angle and the consequent phase lag between the forces appearing at different sections of the mill. Budak and Altintas' multifrequency solution is extended to include the helix effect, and results are compared with results of semi-discretization and experiments.
As a conclusion, the helix has an important influence on the areas of added lobes (flip lobes), while the influence on the traditional lobes is negligible. Flip lobes become closed curves separated by horizontal lines where the depth of cut equals a multiple of the helix pitch.
