CHICAGO (July 14, 4:10 p.m. EDT) — Century Specialties showed a 12-screw extruder at NPE 2000 that is designed for gentle melt processing.
The Traverse City, Mich., company debuted the 3+ Extruder, also called the RE, in North America during NPE. The machine was developed by Blach Verfahrenstechnik GmbH of Lauffen, Germany, which took out four patents on the machine and has more pending.
The 3+ has a fixed core and anywhere from three to 12 screws which rotate around a fixed core. Century product manager Frank Popola said the design provides less shear for processing heat- and shear-sensitive materials. It is suited to reactive extrusion and has a wide range of configurations for venting volatiles. Residence time can be short or long, depending on the application.
The 3+ screws have segmented shear, mixing and kneading elements with a self-cleaning feature. They wipe themselves clean twice with each revolution because the screws intermesh on two sides rather than on one side with conventional twin-screw extruders. Popola said the 12 corotating screws in the extruder displayed at NPE cut down on the number of kneader blocks to allow gentle processing.
One of Blach´s patents covers an irregular, almond-shaped mixing element with one flat tip that lets resin pass from the outer barrel to the inner wall, creating a counter flow. Resin on the outside of the ring of screws travels in one direction along the barrel while resin on the inside along the core travels in the other direction.
The prototype 3+ has been operating at an undisclosed German resin company for nearly two years. Several other machines have been installed at other, undisclosed production facilities. Blach debuted the machine at K´98.
Century has rights to sell the machine in North and South America and eventually plans to manufacture it in the United States, Popola said. Century and Blach started out as extrusion replacement parts producers but have since added complete extruder manufacturing to their services.