Abstract In this study, the effect of modification Al-12Si (Etial 140) casting alloy with Al10Sr, CuSn5, and Al10Sr + CuSn5 master alloys has been investigated with respect to the cutting forces. In order to characterize the morphology of materials used in this study, metallography, hardness, density tests, and chemical analysis were performed. An optical microscope was used to examine the microstructure of the samples. Machinability tests were performed with the turning method by using a titanium diboride-coated cementite carbide cutting tool. All experiments were carried out under dry machining conditions with three different cutting speeds and feed rates with a constant cut depth. After the turning test, scanning electron microscope (SEM) images were used to examine the build-up edge (BUE) formation on the cutting tool. It was determined that the modification process has a positive effect on increasing the density and hardness. According to the results, it was observed that cutting (Fc), feed (Ff), and tangential (Fr) forces decreased for all material groups with increasing cutting speed V. Furthermore, Fc, Ff, and Fr forces increased for all material groups with increasing feed rate f. Finally, the highest cutting forces were observed on the Etial 140 c + Al10Sr master alloy.