A highly unusual, low-energy-consuming, single-screw extruder was shown at K 2007 in Germany last October by Cofit International Srl in Italy (U.S. office in Palm City, Fla.). It defies normal definitions of L/D by reversing melt flow at the end of the extruder, causing it to flow backward and exit from the middle of the barrel.

A highly unusual, low-energy-consuming, single-screw extruder was shown at K 2007 in Germany last October by Cofit International Srl in Italy (U.S. office in Palm City, Fla.). It defies normal definitions of L/D by reversing melt flow at the end of the extruder, causing it to flow backward and exit from the middle of the barrel. The first half of the screw is conventional. Then melt is diverted inside the screw, where it reaches a high-intensity static mixer occupying the last quarter of the screw length. The proprietary Cofit mixer has two concentric, pineappletype mixers. Melt flows first over the inner mixer, reaches the closed end of the extruder (where a die would normally be), reverses direction, and flows back through the outer mixer. Then the melt returns to the outside of the screw, where is channeled back to the midpoint of the barrel and exits from a side port to the die. The inventor of the extruder, Luciano Valotto, is building 25-, 35-, 50-, and 75-mm diam. sizes for customer testing and distribution by Cofit. (772) 215-8087 • www.cofit.com

Cofit International srl
P.O. Box 2238 Palm City, FL 34991
Phone (772) 215-8087 Fax (772) 463-0547