Feed Screws, Designs

Spirex signs screw manufacturing deal with Robert Barr

Spirex signs screw manufacturing deal with Robert Barr

YOUNGSTOWN, OH, Sept. 29 -- Screw producer Spirex Corp. has signed an agreement with Robert Barr Inc. to manufacture and market the Barr Energy Transfer (ET) and Barr Variable Barrier Energy Transfer (VBET) screws.
According to Paul Colby, president of Spirex, the addition of the Barr screws "brings our customers even more options in maximizing production rates at lower temperatures and minimizing wear while consuming less energy."
The Barr ET screw features a patented low-shear mixing geometry in the metering section. Approximately 70% to 80% of the polymer is melted by the high shear, and the remaining solid is melted in the ET section, the company says. Utilizing the natural drag force of screw rotation, the remaining pellets are continuously mixed with the hot melt. The mixing is achieved by low shear without developing undesirable shear or pressure. The remaining pellets melt by the heat conducted from the hot melt by a "conduction melting mechanism," according to Spirex. This allows a much lower melt temperature and higher energy efficiency.
The Barr VBET screw features a unique patented geometry which significantly increases conductive melting and mixing at higher throughput rates. This new low-shear design does not use a barrier section but uses almost half of its length as ET sections, thereby achieving an increase in conduction melting of almost 30%, Spirex claims. In addition, the Barr VBET provides increased production rates, lower melt temperatures, and a more uniform melt temperature distribution on all resins run in production, says Spirex. The VBET is used in blown film, sheet, blow molding, and injection applications.