Milacron Appointed Exclusive Injection Machinery Maker to Manufacture and Sell Performance-Boosting BARR Feedscrews


November 2005 - Milacron has been selected as the exclusive injection machinery maker in the U.S. to manufacture and sell performance-boosting BARR injection feedscrews. The Barr-patented screws - the acclaimed ET® and new VBET® design - are available on new Milacron machines or as aftermarket products from BARR or ServTek, Milacron's "speed shop" for injection units.

"We have had a strong collaborative relationship with BARR, Inc., and we've each come to learn there is a significant synergy that develops when performance enthusiasts from the machinery side and the screw-design side work together," says ServTek General Manager Steve Hayden. "Much like racing, it's one thing to put a high-performance camshaft in an engine; it's another to know how to drive the machine out to the edge of its limits. In one notable instance, we worked jointly with Robert Barr using the VBET screw to reduce cycle times by 1.5 seconds for a molder of 5-gallon pails, by lowering melt temperatures and increasing recovery rates. We've also made significant improvements for other customers processing GTX, Valox, Delrin and flame-retardant PS. We've proven that machinery technology and screw-design science, working together, can deliver higher processing performance for the customer."

The ET and VBET screws can be installed on any injection machine make, model or age. The ET (Energy Transfer) screw has a patented low-shear solid/melt mixing section that uses the natural drag force of screw rotation to cause melt to mix with any remaining pellets so that conducted heat (energy transfer), rather than shear, melts the pellets. About 20-30% of the polymer is melted by conducted heat, instead of shear, so the process is more energy efficient. The result is higher production rates due to an overall lower melt temperature, with greater melt uniformity, according to Hayden.

The VBET screw (Variable Barrier Energy Transfer) takes conductive melting to another level, by increasing the length of the solid/melt mixing section 30-50% over the ET screw design. Almost half its length is an energy transfer section, which increases conduction melting by almost 30%. The VBET energy transfer section melts 30-50% of the polymer by conducting heat from previously melted polymer, eliminating undesirable hot spots in the screw channel. "Melt quality is exceptionally uniform because of the improved mixing and temperature control," adds Ritch Waterfield, ServTek Product Manager. "Energy efficiency is increased as shear energy input is reduced, and the excellent melt is free of hot spots or splay. Overall, the VBET screw yields significantly higher melting rates because its surface area for unmelted pellets far exceeds the solid bed surface area of conventional mixing screws."

For more information on Cincinnati Milacron injection molding machines, ServTek replacement screws and barrels, and other Milacron plastics processing technologies, visit www.milacron.com on the web.

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