The Mixtruder makes it possible to do both the compounding of the plastic and the tubing extrusion in a single pass with a single screw extruder, at a cost negligibly above that of the tubing line alone.
The Mixtruder makes it possible to do both the compounding of the plastic and the tubing extrusion in a single pass with a single screw extruder, at a cost negligibly above that of the tubing line alone. The system is able to offer mixing as good as a twin screw extruder, but in a single screw machine. If users need to introduce a colorant, a radio-opaque additive, a foaming agent, or any other additive to the plastic, they can do a rough tumble-mix at room temperature and then put the mixture into the hopper. Or, a more sophisticated method is to use a multi-component weigh feeder to introduce the appropriate proportions of each component into the hopper.
The key to the performance of the system is the Rauwendaal CRD mixing screw. This introduces two elements missing from standard mixing screws- elongational mixing and reentrant flow. The result has been demonstrated in repeated tests to be equal or superior to the mixing heretofore only available in twin screw machines of two or three times the cost.
With suitable modifications to the barrel and to the hopper arrangement, the system can also handle powder feed stock. This holds out the promise of even further reductions in cost over present methods.
The extrusion systems are available in any Tubetrol extrusion lines, whether for straight tubing, for multi-lumen tubing, or bump tubing.
Harrel, Inc., 16 Fitch St., E. Norwalk, CT 06855. Tel: 203-866-2573. Fax: 203-866-1483.
