In the plastic industry extruders are crucial processing machines. The common processing task, extruders are utilized for, is the melting of polymer pellets. Subsequently the polymer melt is processed by different dies to achieve the desired product shape such as pipes or profiles. For each of these shaping tools various process parameters like pressure drop, melt temperature or throughput have to be accomplished. Because of their self-wiping effect tightly intermeshing co-rotating twin screw extruders are important machines for compounding. The company M-A-S Maschinen- und Anlagenbau Schulz GmbH has developed a new extruder-design. The NCT (new conical technology) is a conical intermeshing co-rotating twin screw extruder with exceptional advantages. Thanks to the conical design the feeding zone of the extruder has a large intake volume. NCT extruders have the ability to process materials with shapes difficult to handle, for example flakes. Moreover it is possible to obtain high throughputs even if materials with low bulk density are processed. As the geometry gets smaller towards the end of the extruder, the NCT has a high pressure-built up at a shorter overall length. Mathematical models of the physical processes inside the extruder give the possibility to target-oriented improvements of the geometry and parameters. The present work deals with the feeding zone and the melting zone of the NCT. The geometry is described by the flat channel model. Because of the conical geometry the screw is divided into small elements, for each element parallel conditions are assumed. The calculation of the maximum throughput of the feeding zone is performed for the Erdmenger profile, the shear edge profile and the box profile. A correction for the bulk density and the maximum solid bed width are included. The melting zone is described by a modified Tadmor model, which takes a location-dependent melt film thickness into consideration. The melt viscosity is assumed to follow the power law and the temperature dependency is considered with an exponential model. The result of the present work is a VBA-program to calculate the maximum throughput of the feeding zone and the melting length as well as the melt temperature at the end of the melting zone. It was found that the melting length is increasing when the cylinder temperature is raised. This effect can be explained when considering that a higher cylinder temperature results in an increased melt film thickness and a lower melt viscosity. Both of these result in a lower energy dissipation rate for the melting process. As calculations show the box-profile has the highest throughput rate followed by the shear edge profile and the Erdmenger profile.