Nine extruders, five layers, one striped, thermoformed yogurt cup
With nine extruders that can be configured to provide numerous stripe and layer combinations, Welex (Blue Bell, PA) says its new five-layer sheet-extrusion system for multicolored food packaging sets a new mark for the number of extruders on one die. Built for a European custom-sheet manufacturer for use in thermoformed yogurt cups, the system has already been shipped and is expected to begin production in April.
March 28, 2011
With nine extruders that can be configured to provide numerous stripe and layer combinations, Welex (Blue Bell, PA) says its new five-layer sheet-extrusion system for multicolored food packaging sets a new mark for the number of extruders on one die. Built for a European custom-sheet manufacturer for use in thermoformed yogurt cups, the system has already been shipped and is expected to begin production in April.
The Welex system produces sheet up to 60-inches (1500-mm) wide with thicknesses from 0.020 to 0.060-inch (500 to 1500 µm) and throughput ranging up to 3000 lb/hr (1500 kg/hr). The nine extruders are from 2.5- to 3.5-inches, with a 30:1 LD ratio and vented, air-cooled barrels featuring two-stage screws to run high-impact polystyrene (HIPS) in a range of colors. The five-layer sheet construction includes a crystal PS gloss layer, a five-color custom-configurable stripe layer, a white layer, a scrap foam layer, and a white bottom layer. The scrap foam layer is produced via a proprietary gas-blown foam process. Welex notes that the system can also run polypropylene with no equipment changes.
Each mobile-mounted extruder includes a slide-plate screen changer and gear pump for high-precision output. The machines feed into a valve-distribution block before the multi-manifold and feed-block-equipped die for easy control of the individual component's destinations.
Welex's Sentinel color touch-screen controls are incorporated into each extruder, as well the sheet take-off unit, with each of those controls patched into the Super Sentinel supervisory workstation via Ethernet/IP fieldbus protocol. Sheet profile is monitored by a Scantech x-ray gauging system, which controls the Welex Autoflex thermal expansion bolt-actuated die. Compared to beta-ray systems, Welex says this gauging method has the ability to measure a smaller area for more precise measurement and control.
The sheet extrusion line's Welex Evolution individual roll drive sheet take-off system also has automatic roll-gap controls and a set of water-flow-driven secondary cooling rolls to promote uniform sheet temperature at the end of the line prior to winding onto jumbo rolls.
Welex multilayer sheet-extrusion system.
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