High-alloyed white-cast-iron materials are commonly used in the manufacturing industry due to their high wear resistance. The aim of this research is to determine the cutting tool and the optimum cutting conditions required for the metal cutting of these materials. In this study, it is proposed to determine the wear and the tool life utilizing the Taguchi optimization method when hard turning the Ni-Hard 4 material, the alloyed cast iron, with cutting tools produced with powder metallurgy (PM) and to improve the performance of the cutting tools. A series of 18 experiments were conducted on a CNC turning machine, using the cutting process parameters such as the cutting speed, the feed and the depth of cut, based on the Taguchi L-9 orthogonal design of experiments. Uncoated cutting tools were utilized to perform these experiments. PM cutting tools with WC grain sizes of 0.8 mu m and 1.25 mu m were selected for the hard-turning experiments. The flank wear of the cutting tools was examined with SEM. Then, the life of each cutting tool was identified based on the cutting length. The performance of the cutting tools in terms of the wear and the tool life was determined with the Taguchi method based on the obtained data. The results of this study contributed to the hard turning of the Ni-Hard 4 material that is mostly employed in the as-cast condition in the manufacturing industry due to its high hardness. The optimum cutting conditions were determined by means of the Taguchi method.