Modeling dynamics and stability of variable pitch and helix milling tools for development of a design method to maximize chatter stability

Official URL: http://www.elsevier.com/locate/precision

Chatter is one of the major limitations in milling operations causing poor quality and reduced productivity.Stability diagrams can be used to identify deep stable pockets which usually occur at high spindle speeds.However, the required high cutting speeds may not be applied in some cases due to machinability ormachine tool limitations. It is known that variable pitch and helix tools help suppressing chatter even atlow cutting speeds. These tools may offer high productivity if they are properly designed. The literatureon variable geometry milling tools is mainly limited to modelling and simulation whereas for industrialapplications design guidelines are needed for selection of variation pattern and amount which is thefocus of this paper. Dynamics and stability of variable pitch and helix tools are modelled and solved infrequency domain as well as using Semi-Discretization Method employing multiple delays. A practical butaccurate design method is presented for selection of the best variation combination to maximize chatterfree material removal rate without using time consuming computer simulations. Increased stability withthe tools designed using the proposed method is demonstrated by several examples which are verified experimentally.