The simulation of proceedings in an extruder becomes more and more important for the perfect coordination of production-machines in order to achieve a more complex function. With the help of models, which describe the processes in an extruder, it is possible to coordinate the screw geometry with the material. For the developement of models respectively for the numerical simulation it is necessary to know a number of material data. Within the melting-zone the length of the delay zone depends mainly on the penetration depth of the melt in the bulk.
Within the scope of this paper the dependence of the average melt penetration depth on the bulk-temperature and pressure has been examined.
As a result of this research it can be concluded, that the influence of the melt penetrated in the bulk has very little influence on the length of the delay zone. Especially the results of experiments with rigid materials have shown, that there is no influence at all and it can be neglected for the
calculation. Although in the case of softer materials a minimal influence has been observed.