A novel instantaneous uncut chip thickness model for mechanistic cutting force model in micro-end-milling

Abstract

Modeling of cutting force plays a vital role in characterizing the micro-end-milling processes, including tool wear and surface quality as well as machining stability. It is well recognized that precise determination of instantaneous uncut chip thickness (IUCT) is essential for cutting force prediction, while the presence of tool run-out and material elastic recovery have an equally important influence. On the basis of the IUCT model considering run-out, elastic recovery is innovatively integrated into the surfaces generated by the previously passing tool tips to improve the accuracy of IUCT model. Subsequently, a novel IUCT model is proposed in this paper that considers trochoidal trajectory of tool tip, run-out, minimum chip thickness, elastic recovery, and variety in entry/exit angles. Also, it can be found that the elastic recovery has a significant effect upon IUCT (especially at small feed rate) based on the numerical analysis of the IUCT model, and meanwhile the role of elastic recovery is mainly affected by run-out, minimum chip thickness and elastic recovery rate. Furthermore, it is worth noting that entry/exit angles may change at small feed rate when taking into account elastic recovery. Then, the IUCT model and non-linear cutting force coefficients are integrated into the mechanistic cutting force model and used to predict cutting force. The predicted cutting force is found to be well in harmony with the experimental results; as a result, the developed theoretical cutting force model in this work can be used in real-time machining process monitoring as well as adaptive control of machining process.