REX calculates the temperature in the melt vortex and in the melt film for each interval after the location of the melt vortex formation (OSW). As melting progresses, the constantly growing melt film becomes thicker and at the same time is scraped off by the screw flights. This not only makes the melt vortex warmer due to barrel tempering and shear dissipation, but also takes into account the mixing with the generally cooler melt film. As a result, the temperature increase per unit length of the screw during melting can be lower than after melting.