<p>Accurate prediction of milling forces is crucial for evaluating tool life and surface quality in 5-axis ball-end milling, especially during finishing operations. Optimizing machining processes and cutting parameters is the master key to achieving higher precision and efficiency. This paper presents a new modeling of the cutter workpiece engagement region (CWER), the contact area between the tool and the workpiece, that considers an accurate calculation of Instantaneous Uncut Chip Thickness (IUCT). These developments are used to propose an improved cutting force model for ball-end milling. The presented models account for the influence of tilt and lead angles, providing a more accurate representation of the impact of tool inclination on chip geometry compared to traditional models. The cutting force components for each cutting edge are calculated using a mechanistic approach, offering better precision in force prediction. The model has been thoroughly validated through multi-axis milling experiments and compared to previous studies. Results show that the proposed model significantly improves milling force prediction, making it a valuable tool for enhancing tool life and surface quality in ball-end milling.</p>