It is important to have adequate controlled heating of the die adapters and connecting flanges. With unheated flanges, so much heat may be dissipated that the temperature in this area drops too heavily.

The flow channels must be designed so as to encourage good flow (i.e. without any dead spots), and the cross section should be geared to the mass flow rate. For the same reason, leaps in pressure must be avoided at all costs.

In long adapters, static mixers have proved useful for maintaining transverse mixing as they ensure greater uniformity of temperature and color dispersion in the melt. The use of strainer disks with and without a screen pack is of course also a possibility (Fig. 1).

Fig. 1: Example of a strainer disk with a screen pack