The advent of stretch-film products comprised of five or more coextruded layers, coupled with the demands of a highly competitive industry, place special requirements on the performance of extrusion die systems. One reason is that flat dies for the production of stretch film are typically 3.1 meters (124") or 3.7 meters (145") wide to accommodate five- or six-up finished roll arrangements respectively. At these slot widths, facilitating precise distribution of the multi-layer structure while at the same time addressing pressure and residence time considerations presents a challenges. Second, in addition to total gauge uniformity, layer-to-layer uniformity must be maintained to ensure that the stretch-film product meets end-use performance requirements and, equally important, to control raw material consumption. And third, competivie forces have driven producers to operate at very high throughput rates with long production runs, making unscheduled downtime extremely costly. Die system reliability is critical in meeting all of these process demands.
展开▼
