Plunge milling is used increasingly in the manufacture of molds and dies for opening pockets due to its advantages over end milling. Because it is a rough operation, it involves high material removal rates and strong cutting forces. In this context, this article reports on a study of the static and dynamic behaviors of the forces involved in the process. In addition, a cutting force model is developed based on the kinematics of the process and the tool’s special features to predict the mean forces generated during the plunge operation. Low sensitivity of the static force components of tool flank wear and minor influence of the system on the dynamic behavior of the process are observed. The model shows good agreement with experimental results.