EDI Press Release

EDI MAKES UNIQUE CONTOUR DIE™ DESIGN STANDARD FOR ALL
OF ITS NEW CAST FILM SYSTEMS

Die Is ‘Revolutionary’ for Its Capability to Adapt Rapidly to Each New Product Run without Sacrificing the Flow Streamlining that Is Essential for Film Quality

MILAN, February 14, 2006 - A revolutionary die that yields thousands of kilograms of additional saleable product with each new job run or major throughput change is now the standard for all cast film systems shipped by Extrusion Dies Industries, LLC (EDI), the company announced today at Plast (Hall 13, Stand C10).
Called the Contour Die™, the system has become the preferred die for EDI’s cast film customers, who have ordered nearly 60 units since the concept was introduced three years ago, according to Sam G. Iuliano, product manager for the cast film industry. “In extensive use for commercial cast film production, the Contour Die has consistently reduced the time to adjust for changes from one product to another from 40 minutes or more to five minutes or less, yielding large quantities of good, saleable film that would normally have been scrap,” said Iuliano. “This increased productivity is available without the sacrifice of melt flow streamlining that has characterized previous ‘uniform-deflection’ dies.”
The deflection cited by Iuliano refers to distortions in the die gap caused by changes in material viscosity or throughput rate with switches from one product to another. Because the pressures inside the die are high, these changes cause the heavy steel die bodies to deflect. In a conventional cast film die, the deflections are non-uniform, typically causing the lip gap to open more in the center than at the ends and producing a distortion in the product commonly called “clam-shelling.” In designing the Contour Die, EDI solved this problem by giving the die a unique “sculpted” shape, thicker in the center than at the ends, that produces uniform deflection.
“With each product changeover, the operator of a conventional die typically must offset non-uniform deflection by shutting down the automatic gauge profile control (APC), manually adjusting the lip gap, and then restarting the APC for final tuning,” said Iuliano. “With the Contour Die, the APC itself is sufficient for adjusting the die to dramatic changes in material viscosity or throughput.”
Over a year’s time, this increase in productivity and reduction in scrap can yield substantially improved profitability for the film manufacturer, according to Iuliano. “By eliminating much of the penalty incurred with job changes, the Contour Die enables film companies to compete effectively in a marketplace increasingly characterized by short run times for highly customized films,” said Iuliano. “And since the clam-shelling problem increases with width in a conventional die, there are special benefits for companies that employ very wide dies.”

Contour Die™ Provides Uniform Deflection without Sacrificing Streamlined Flow
The concept of changing the overall shape of the die from the usual block-like configuration is a radical departure from conventional dies, including previous “uniform-deflection” systems, which involved changes to the manifold, or flow channel, inside the die.
While the workhorse manifold for cast film has been the “coat-hanger” (so called because of the triangular shape of the flow channel), designers first attempted to solve the clam-shelling problem with a “broad shoulders” manifold shaped so that the bolts clamping together the two die halves, or bodies, were arranged in a straight line. By making the bolts equidistant from the die exit, this design yielded uniform die body deflection—but at the cost of flow streamlining. Molten polymer—particularly highly elastic material—tended to stagnate in the corners at each end of the manifold. The difference in residence time between material exiting from the center of the die and material exiting from the ends could cause variations in strength or puncture resistance across the width of the film, or even yield discoloration at the ends.
“In designing the Contour Die, EDI engineers started with a standard coat-hanger manifold to ensure streamlined flow and then developed a new shape for the die bodies enclosing it,” Iuliano said. “Besides making possible rapid achievement of target gauge, the resulting combination of uniform die body deflection and streamlined flow provides greater leeway for increasing extruder output without compromising product quality and consistency, reduces the possibility of polymer degradation and gels, and speeds up purges for color or product changes.”

CAPTION, PHOTO 1: Tapered shape of new Contour Die™ is designed to yield uniform die body deflection while incorporating a manifold that maximizes flow streamlining. To offset greater internal pressure at center of die, die body is heavier there and lighter at either end. Die is shown with lips pointing downward. Projecting obliquely toward the left is Autoflex® VI-R automatic gauge profiling system. Behind the die (projecting upward) is Accuflow I-S Feedblock.

CAPTION, PHOTO 2: One half of “coat-hanger” manifold, with triangular flow channel and holes for body bolts arranged obliquely with respect to the lip exit.

CAPTION, PHOTO 3: One half of “broad shoulders” manifold, with holes for body bolts in a straight line.