The paper presents research conducted with the purpose of optimising the chemical composition of cast irons used for the casting of bearing ball machining disks. Exploitation characteristics of these cast irons were taken into consideration, as their durability in ball machining and their capacity of ball machining. The link between these characteristics and the chemical composition of the cast irons was achieved by the Ni contents, the carbon saturation degree Sc and the equivalent eutectic carbon Ccq. The paper describes the types of used test pieces, working conditions and presents the interpretation of the experimental results (second degree polynomial regression curves) as well as the consequent conclusions.
