An extremely important role in modeling shaft - bearing systems, whether it's purely mechanical applications (motors) or medical applications (micro-milling spindles in orthopedics or dentistry), is represented by the bearings. They are the main cause of heat generation in the whole shaft-bearing assemble, but they also bring a major contribution to the radial force of thermal preload, deformations of the shaft or vibrations. Optimization of rotating shafts often gives possibility to adjust the performance but also to increase the service life of the milling tool, as a function of preloading of bearing, which is particularly important in orthopedics due to the overloading of assembly during the surgical act. The forces acting on the bearing, whether of mechanical origin (the force of strain) is due to the thermal effect generated by the friction of the balls on the inner / outer ring and the lubricant used, result in a change in the ball bearing contact angle effect in the overall system analysis. Moreover, dynamically, this angle also changes as a result of external negligible effects that can be considered for a more accurate or neglected model in the case of an approximate model (e.g. centrifugal force, moments, effect gyroscopic, etc.). Advanced graphical interface, calculates the value of the angle on the outer and inner ring, based on the revolution of the axis. The model can be simplified or complicated by giving the user the possibility to include factors that raise the accuracy. This allows you to define the geometric dimensions of the bearing, material constants, the revolution values for which a dynamic analysis is being performed, and graphic display selection of angles as well as export values in tabbed format to be used in other industry-specific applications.