Although 5-axis free form surface machining is commonly proposed in CAD/CAM software, collision detection between the tool and the part with smooth tool axis reorientations still need to be addressed. In this paper, a physically based method using potential fields is developed to generate 5-axis collision-free smooth tool paths. The ball-end tool is considered as a rigid body moving in 3D space on which repulsive and attractive forces are acting. Investigations are carried out to set-up the simulation parameters and prevent the tool axis orientation from oscillating and to ensure a smooth behavior.