<p>This work aims to conduct an in-depth analysis of cutting force fluctuations during robotic milling, with a particular focus on the impact of axial force fluctuations. It reveals a direct correlation between these fluctuations and surface defects. Specifically, in the arc transition regions and at the tangent points, axial force peaks can lead to overcutting and tool lift, resulting in irregular tool marks and surface height variations. Additionally, magnified cutting force fluctuations cause instability in cutting depth, further exacerbating surface defects. The study further explores that the abrupt changes in axial force in the arc transition regions primarily stem from the misalignment between the cutting force direction and the dynamic response direction of the robot, resulting in insufficient stiffness and delayed posture adjustments. The findings offer novel insights into the complex relationship between cutting forces and surface morphology, providing valuable guidance for optimizing tool paths and milling parameters to enhance surface quality in robotic milling applications.</p>