Co-extruders with weigh hoppers
Features
The task of gravimetric control in co-extrusion is to keep the throughput of each extruder constant. Therefor each extruder is equipped with a weigh hopper to measure the individual throughput.
This units can be implemented at any time by placing them between extruder inlet and storage hopper.
To support the material feeding usually a frame is build over the extruder to take all heavy units without disturbing weight measurement.
Co-extruder with side component
Features
The throughput of an extruder can also be measure, if a blend unit is mounted on the extruder inlet for direct blending.
As shown here the blender has a free flowing main component (left) and a side component for masterbatch (right).
The total throughput is added from both components. Accordingly extruder's screw speed can be controlled to the total throughput.