Due to the fact that the processing of rubbers is often based on the principle of “trial-and-error”, this thesis is supposed to investigate the possibility of creating mathematical models to describe certain processes. Using a specifically constructed test stand the following investigations are made according to a Design of Experiments (DoE). The temperature profiles inside the barrel of the injection unit as well as the cross flow which develops along the screw channel are examined. The goal is to find models which can be used to create a plain temperature profile in order to enhance part quality. Another objective is to predict the way the cross flow develops and to find the responsible factors which influence the cross flow. The experiments are conducted with the factors feed temperature, barrel temperature, rotation speed and back pressure being varied. Models are found which are able to not only describe but also predict temperature profiles accurately as long as predictions are within the range of the DoE. Furthermore, an almost plain temperature profile can be created using a rotation speed profile. A description of the development of cross flow by means of mathematical models was not possible due to significant non-linearity of the experimental results. As essential influencing factors affecting the development of the cross flow barrel temperature, rotation speed and back pressure were identified.