Minimizing workpiece vibrations is one of the greatest challenges in milling. Vibrations lead to surface damage on the workpiece, to more complex finishing operations and to increased tool wear. However, the vibration behavior of workpieces is complex: During milling, the mass and stiffness of the workpiece change continuously due to material removal. The vibration behavior is dynamically variable and depends on the tool position and the cutting force. Current CAM systems are not able to map this complex behavior, which is why process planners face unsolved problems when selecting process parameters.
In the "PhysiX-CAM" research project, the Fraunhofer IPT is developing CAM software for predicting the vibration behavior of thin-walled workpieces. To this end, the researchers are combining geometric and numerical process models by combining material cutting simulations in the milling process with physical FE simulation. The "PhysiX-CAM" software is intended to enable the prediction of the workpiece vibration behavior already during CAM process planning. This enables process planners to select advantageous process parameters that lead to minimal vibration amplitudes. The aim is to optimally configure milling processes for resource-saving and economical production.
To achieve this goal, the researchers are coupling a material cutting simulation, a cutting force simulation and an FE simulation. In this way, they create a virtual environment for the simulation and optimization of workpiece vibration behavior. In addition, the researchers are developing new modelling strategies for generating geometric, qualitative representations of the workpiece during milling. These workpiece representations can be efficiently used in FE simulations to determine natural frequencies and vibration modes.
Through the integration of a cutting force simulation, externally and self-excited workpiece vibrations can be simulated at specific points in time during the cutting process. At these points in time, milling can then be carried out with minimal vibration amplitudes by automatically changing process parameters, such as the spindle speed.
In the next step, the researchers use the simulations to investigate new material processing strategies, such as continuous speed variation during milling. In this way, the researchers hope to achieve optimized and vibration-reduced real process states in addition to the previously simulated discrete points in time.
The "PhysiX-CAM" project is funded by the European Fund for Regional Development (EFRE) 2014-2020.