Have you ever wished that you could extrude a tube which is made from one polymer at one end and another polymer at the other end -- all without having to join two separate tubes together?
The new AP-600 ALTERNATE POLYMER extrusion system from Harrel, Incorporated can now do just that. You can start with a tube made 100% from polymer "A" and change the composition seamlessly to polymer "B". The transition will be tightly programmed. The outside and the inside diameters of the tubing may be the same for the two polymers, ifdesired, or either or both may be changed independently, according to any desired program.
Polymers "A" and "B" may be different durometers of the same polymer, or they may be entirely different. Polymer requirements are the same as for any coextrusion application -- the two polymers must be compatible. The system is not limited to two components. It can be adapted for 3 or more polymers.
The degree of sophistication in the control systems for the ALTERNATE POLYMER system obviously needs to be quite high. As a practical matter, total system control from an overall system processor is absolutely required to coordinate all of the system elements. In addition, very special forms of the extruders and several of the downstream elements are required. Harrel is, therefore, offering this system as a packaged, turnkey system. Plastic goes in one end, and a finished ALTERNATE POLYMER tube comes out of the other. Systems are set up in the Harrel laboratory and run by customer personnel before shipment.
A high degree of automation is built into the AP-600 systems. It simply would not be feasible to operate a system of this complexity on a manual basis. With the controls provided, however, no special skills are required.
The system pictured has an output of 15 pounds/hr (6.8 kg/hr) and is intended for the medical and similar industries. There are, however, no limitations on the output when larger extruders are used. The ALTERNATE POLYMER principle (patent applied for) may also be used in applications other than tubing. It is equally applicable to profile, sheet, blown film, or any other form of extrusion.