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CHICAGO — A new generation of high-throughput compounding extruders are featured by Berstorff Corp. (Booth N5507) and Werner & Pfleiderer Corp. (Booth S2367).

Berstorff is showing its Ultra Torque technology for the first time in North America. The ZE 75-A Ultra Torque model at NPE in Chicago can provide double the output of conventional models, the firm claims.

W&P makes similar claims of double or more increased output for its Mega compounder, the sixth-generation ZSK twin screw for processing a wide variety of polymers.

Berstorff's new machine is a compact extruder that runs at a standard 600 revolutions per minute with options to double the speed. It can process most engineering resins at rates of 2,500-6,000 pounds per hour, according to the Charlotte, N.C., firm.

Gene Stroupe, the firm's vice president of compounding, said a new screw shaft design and gearbox design for added torque and strength are key to Ultra Torque's performance. High torque is especially beneficial for heat- and shear-sensitive materials such as thermoplastic elastomers, alloys and glass-filled compounds, he said.

``We maximize melting and mixing in Ultra Torque,'' Stroupe noted.

Multispline screw shafts combined with screw shaft geometry and optimized screw elements give high volumetric conveying capacity at high mechanical strength to match the increase in torque.

Ultra Torque gearboxes have top openings for simpler maintenance and reduced downtime. Berstorff offers a range of power configurations for flexibility.

W&P says its Mega compounder has a smaller footprint and lower investment cost per pound of output. Mega's 30 percent higher torque than previous extruders and higher speeds increase productivity by at least 40 percent, according to the Ramsey, N.J., company.

W&P maintained its outside-diameter-to-inside-diameter flight/ depth ratio at 1.55 because it optimizes free volume and shear conditions, said sales director Asmut Kahns. That allows high speeds without increasing stress on resins. The Mega machine heats product more gently at high speeds than W&P's previous generation of Super Compounder twin screws.

A redesigned gearbox, spline, shaft and elements allow the increased mechanical capabilities of the Mega line, Kahns said.

Kahns said Mega compounders are popular in North America and Europe and now account for most of W&P's twin-screw orders.

``People are always looking for ways to expand, and Mega gives them more output for their investment dollar,'' he said.

W&P is displaying a 58-millimeter Mega machine at the show. The extruder will go to Chemtrusion Inc.'s Houston toll compounding facility after NPE. It will be the fourth W&P extruder at Chemtrusion's Houston plant and the eighth W&P twin screw operated by Chemtrusion.

W&P also is showing its new ZSB twin-screw side feeder for difficult-to-convey materials. The feeder is designed to accommodate the high throughput of Mega extruders.

Stroupe said Berstorff's Ultra Torque extruder has been a hot seller since it was introduced at the K'95 show in Dusseldorf, Germany. It has sold 110mm versions, but most-popular are 60, 75 and 90mm extruders.

Stroupe said many compounders are pushing their conventional extruders to the limit and the new twin screws can help them avoid breakdowns while increasing production.

W&P's booth also features its new ZSK 25 World Lab Extruder, a twin screw available in speeds of 600 and 1,200 rpm.

The research machine will have K-Tron America Soder compact feeders designed for low-rate, microingredient feeding of pellets, pigment powders and other materials.