Development of a Mechanistic Force Model for CNC Drilling Process Simulation

This paper presents a methodology to obtain force information during CNC machining simulation for drilling process especially when the workpiece is inclined to the drill axis or has internal cavities. First, a mechanistic force model is introduced to relate drilling forces to drill geometry and drilling process parameters. Next, an algorithm is introduced to calculate contact boundary between drill point and workpiece especially when the workpiece has irregular shape for each step. Finally, maximum drilling forces for each drilling step are obtained by applying the mechanistic force model to the calculated contact boundary. The model is demonstrated on and validated with designed cases. The results show that the mechanistic force model can predict the drilling forces accurately with varying drill geometry and process parameters and the model can deal with drilling into irregular workpiece.