Model-based Investigation of Thermal Loading in Milling Processes Including Chatter

AbstractIn the machining of large structural components such as those used in the construction of airplanes, most of the material is removed, while at the same time, a large amount of heat is inserted into the workpiece. During roughing operations in dry milling, the thermal load can lead to workpiece distortions that result in a violation of the manufacturing tolerances of the finished part. Although the variation of process parameter values and milling strategies can influence and significantly reduce the thermal loading, effects such as chatter or limitations of the machine also have to be taken into account.In this paper, the interrelation between process parameter values and dynamic tool behavior is investigated, as both have a large influence on the thermal loading of the workpiece. Milling with a high material removal rate typically results in a lower heat input into the workpiece, but this approach is limited and may lead to process instabilities, manifested in chatter of the tool.In this paper, a basic experimental analysis for the influencing process parameters feed per tooth fz, axial immersion ap, radial immersion ap, and spindle speed n is conducted, and the effects of chatter on the thermal loading of the workpiece is analyzed by experiment. A geometric simulation of the milling process is utilized in order to reduce the experimental effort, as well as to to increase the knowledge of the heat input mechanisms. The simulation system is able to calculate the transient dynamic behavior of the tool with high accuracy and can therefore be used to predict the process stability in advance. Additionally, a thermal model is used to simulate the temperature of the workpiece material during the dry milling process