The master`s thesis presents the optimization of the process parameters of the 3-axis milling. The main goal is to obtain the required roughness in the range of 0,2 μm and 0,4 μm with maximum process productivity. The workpiece is made of tool steel OCR12VM (1.2379). The master thesis describes the process of preparation of the 2 experimental samples, the processing strategy, the design of experiments, experiment preparation, roughness measuring, process parameter optimization, durability checking of the CBN ball end mills and cost analysis. Due to the desire of getting better surface quality and increase the process productivity, we used the method design of experiment and tested the ability of 2 CBN ball end mills. We have found that with both cutters we achieve our main requirement of surface quality. But in addition, through experimental work and analysis, we have also come to the conclusion that cutters differ in the influence of processing factors, productivity and stability of the process and the required processing cost.