Predicting regenerative chatter in milling with hardware-in-the-loop simulation using a dexel-based cutting model

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This article proposes a new model for simulating the interaction between cutting process and machine tool in real-time. The purpose of the model is to be coupled with a real CNC (by using hardware-in-the-loop simulation) in order to consider process forces and to predict regenerative chatter vibrations during virtual commissioning. Therefore a dexel-based workpiece model with adaptive resolution is used for the computation of the chip thickness respectively the cutting forces based on the actual machine tool position and the machining progress on the workpiece. Several simulation experiments are performed to validate the model and to analyze its numerical limits, such as computational accuracy and efficiency. The capability of the model to predict chatter is proven by comparing the simulated critical depth of cut with an analytical solution of the stability lobes. Therefore the dynamics of the machine tool were approximated as a single degree of freedom (SDOF) oscillator. A concluding analysis of the real-time factor confirms the model’s ability to be integrated under hard real-time requirements and with cycle times of just a few milliseconds which are typical of CNCs.