An analytical design method for milling cutters with nonconstant pitch to increase stability, part 1: Theory

Chatter vibrations result in reduced productivity, poor surface finish and decreased, cutting tool life. Milling cutters with nonconstant pitch angles can be very effective in improving stability against chatter In this paper an analytical stability model and a design method are presented for nonconstant pitch cutters. An explicit relation is obtained between the stability limit and the pitch variation which leads to a simple equation for determination of optimal pitch angles. A certain pitch variation is effective for limited frequency and speed ranges which are also predicted by the model. The improved stability, productivity and surface finish are demonstrated by several examples in the second part of the paper.