The contribution analyzes the causes of the residual stress in the material during face milling. It focuses on characteristics of internal tension in materials (causes of occurrence, consequences), influence of cutting conditions, machining strategy and possibilities of removal / elimination of internal tension. The experimental section of this article deals with the measurement of internal stresses during face milling of samples (comparison of the aluminium alloys of groups 5th, 6th and 7th) before and after the heat treatment using the method of drilling holes using tensometric rosettes. Part of the contribution is also devoted to the comparision of milling tool diameter influence on the machined surface of sample flatness. The article ends with a discussion that evaluates the achieved results from a practical point of view, an overall conclusion of the results achieved with the problems that arose during the measurement and the final recommendation.