In this paper, the performance of machining processes on ductile cast iron (DCI) was investigated. There were 3 DCI specimens made with variations in the amount of graphite per mm², graphite size and percentage of pearlite and ferrite. The machining performance was measured is by cutting force, feed force and tool wear. The machining process was carried out at various cutting speeds from 45 – 120 m/min, a feed of 0.1 to 0.3 mm/rev and a depth of cut of 1 mm. The results obtained show that the machining process of ductile cast iron is influenced by its microstructure, where the amount and size of nodular graphite is more dominantly affecting the cutting force and feed force, while the percentage of ferrite and pearlite is more influential on tool wear.