This paper presents a study on enhancing the surface flatness quality induced by CNC milling machines based on optimizing the toolpaths. Continued from our previous research in the relations between surface variation patterns, cutting forces, process variables, this study iluminates an idea of cutting path planning as a feasible approach for enhancing surface flatness. The algorithm to calculate the optimal cutter path is given, aiming to balancing the cutting loads on the cutter, a factor that reduces surface flatness. A cutting experiment as a case study illustrating the assumptions were conducted with the surface flatness improvement of about 15-25%. The data used in this study is obtained from measurment using an advanced high-definition metrology (HDM) system
