Models of technical systems play an essential role from the conceptual phase to the end of life of the system, as they allow the prediction of the behavior of the real world instance by simulation. Time and money spent on building prototypes can be saved, and the development process can be significantly accelerated. Furthermore, simulations allow the optimization of systems in advance.A major problem in modeling modern systems is complexity, as machines increasingly include components from different areas such as cooling systems, active bearings, etc., along with the control units that govern the interaction. The model must incorporate all these systems and reflect their behavior with sufficient accuracy. This results in the need to modularize the modeling process and create a model from all these sub-modules.Within the framework of the Collaborative Research Center/TR96 (CRC/TR96), a methodology has been developed to solve the above problems. It enables the coupling of several sub-models to a complex system model. The methodology is described together with the open-source and proprietary tools used to facilitate all necessary modeling and simulation steps.As an example of the application of the described methodology, the modeling and simulation of a complete machine tool is presented. Special attention is given to the modeling of the moving part contacts, since they have a significant influence on the simulation result. Different approaches for contact modeling are compared.Finally, the next steps for transferring the developed methodology to practical applications are outlined.