Cutting forces with respect to different cutter orientations are analyzed for five-axis NC machining of a ball-end cutter.A measure is then defined to quantify the effects of cutter orientation variation.According to the measure,a novel model and algorithm are proposed to wholly optimize cutter orientations based on a cutter contact(CC) point mesh.The method has two advantages.One is that the cutter orientation smoothnesses along the feed direction and pick-feed direction are both wholly optimized.The other is that only the accessibility cones of mesh points are required to compute and the computation efficiency is improved.These advantages are shown by simulating the machining efficiency,the stability of feed velocities and the smoothness of cutting force.A computational example and a cutting experiment are finally given to illustrate the validity of the proposed method. Cutting forces with respect to different cutter orientations are analyzed for five-axis NC machining of a ball-end cutter. A measure is then quantified the effects of cutter orientation variation. Accroding to the measure, a novel model and algorithm are proposed to wholly optimize cutter orientations based on a cutter contact (CC) point mesh. The method has two advantages. One is that the cutter orientation smoothnesses along the feed direction and pick-feed direction are both exclusively optimized. the other is that only only the accessibility cones of mesh points are required to compute and the computation efficiency is improved. The advantages are shown by simulating the machining efficiency, the stability of feed velocities and the smoothness of cutting force. A computational example and a cutting experiment are finally given to see the validity of the proposed method.