In this study, machining tests of the bearing necks of crank shafts produced from GGG-70 grade ductile iron (DI) are carried out. Coated cemented carbide inserts are used in the machining tests. The tests are carried out at four different cutting speeds (250, 275, 300 and 325 m/min), three different feed rates (0.15 0.25 and 0.30 mm/rev) and two different depth of cuts (0.5 mm and 2 mm). The effects of these parameters on the surface roughness and the cutting force are investigated. Increasing cutting speed is found to deteriorate the Surface roughness. The best average surface roughness values are obtained at 250 m/min which is the lowest cutting speed. Main cutting forces increased with increasing iced rate and depth of cut.