Geometrical analysis of thread milling-part 2: calculation of uncut chip thickness

Thread milling offers interesting possibilities for machining internal or external threads. This machining technique uses a mill with a triangular profile for metric threads and a helical interpolation strategy. Thus, the uncut chip thickness cannot be easily evaluated from a simplified approach. The present study deals with a model for calculating uncut chip thickness during internal thread milling. This step is needed to understand and model the cutting forces. The model developed uses the geometrical definitions of the mill and takes into account the milling mode and the cutting conditions. The link with the interferences between the tool and the thread is also established and corroborates a previous study. A full analytical formulation of the problem is proposed, and results from different milling settings are presented.