AbstractThe ability to plan the quality of surfaces is very important in manufacturing due to the fulfillment of requirements for parts machined by different methods. A method and a modelling procedure are introduced in the paper based on the definition of the relations between the calculated theoretical and the measured real roughness values of machined surfaces. Cutting experiments were performed for the determination of the real roughness data where the evolution of surface roughness was investigated with varied technological parameters. Finally, the calculated relations between the theoretical and real values are presented,allowing the prediction of the expected roughness of surfaces machined with the given conditions.