Dynamics and stability of 5 axis ball-end milling using single and multi frequency solutions

Being one of the most important problems in machining, chatter vibrations must be avoided as they result in high cutting forces, poor surface finish and unacceptable part quality. Using stability diagrams is an effective method to predict chatter free cutting conditions. Although, there have been numerous works in milling dynamics, the stability of 5-axis ball-end milling has not been studied in detail. In this paper, stability of the 5-axis milling is analyzed using analytical (frequency domain), numerical (time domain) and experimental methods. A single-frequency method is used to generate stability diagrams in the first part whereas the multi-frequency dynamics of the process and its stability are considered in the second part. The analytical model presented considers 3D dynamics of the 5-axis ball-end milling process including effects of all important process parameters such as lead and tilt angles. Due to the complex geometry and mechanics of the process, the resulting analytical equations are solved with an iterative procedure in order to generate the stability diagrams. The predicted stability diagrams are compared with experiments. Using the model and experimental results, the effects of lead and tilt angles on stability diagrams are shown. The presented model can be used in analysis of 5-axis milling stability as well as selection of milling conditions for increased stability.