In polymer processing, especially in injection molding and extrusion, the plasticizing unit is a major functional component. To ensure high output rates in association with good melt quality, further development regarding to plasticizing screws, is essential. There are few commercial simulation programs, but their results are often inaccurate and troubleshooting has proved to be difficult. Therefore, a new simulation software was developed to predict the optimum screw geometries and process parameters for the respective applications. The focus of this work is on standard three-section screws, which are the most common. At first, extensive material characterization and appropriate material models are the basis for high quality process simulations. Hence, several observations with different measurement devices were conducted for determining thermodynamic and rheological material parameters. Secondly, the three-dimensional helix shape of the screw channel consisting of feed, compression and metering section can be approximated via an unwrapped screw channel [1]. Afterwards, a 2D grid generator is used to divide the unwrapped channel in numerous small grid cells. The screw pitch, channel height and flight number can be variable along the axial screw length as well as further geometry parameters. Finally, the simulation can be examined by using a clear separation of the melt and solid fraction, several mathematical and physical models, especially the finite difference method, the melting model based on Tadmor and Gogos and a numerical temperature calculation based on Miethlinger and Aigner [2]. The axial screw motion during the plasticizing process and the idle time due to the cooling cycle are considered as well. The simulation output includes the pressure/throughput behavior, melting behavior, temperature development and power consumption. In addition, the obtained results have been compared with a commercial software and verified with suitable experiments.