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Controls push speed limit

U.S. Sugar fills two 5-lb bags/sec with better than ±0.1% accuracy thanks to a state-of-the-art sugar-filling line powered by the latest in servo drive, PLC and networking technology.

Moving spouts (inset) travel with the bags as they fill three bags simultaneously. The entire packaging line (above) is controll
Moving spouts (inset) travel with the bags as they fill three bags simultaneously. The entire packaging line (above) is controll

In designing high-speed packaging lines, engineers eventually reach a point where they must sacrifice accuracy for speed. U.S. Sugar, with its two high-speed sugar bagging lines, found a way to keep both speed and accuracy.

Each of the two lines forms, fills and seals two-layer paper sacks on equipment from SIG Pack (Raleigh, NC). One line fills at a top speed of two 5-lb bags per second.

Further, accuracy is extremely high, better than ± 2 g on a 5-lb (2곬-g) bag, according to Dave Pelham, chief of bulk shipping, warehousing and packaging. That works out to be a variance of less than a tenth of one percent. U.S. Sugar attributes much of the extremely high filling speed and accuracy to the state-of-the-art controls from Siemens (Alpharetta, GA).

Packaging World recently visited the year-old packaging lines near the Florida Everglades where U.S. Sugar’s plant is located. Long a processor of raw cane sugar, U.S. Sugar had decided to enter the sugar refining and packaging business instead of selling its raw sugar to other firms. That’s what prompted construction of the Clewiston, FL, plant and the packaging lines contained within, which were put into production in March 1999.

On the day of PW’s visit, U.S. Sugar was packing 5-lb bags of sugar for Pillsbury on the line dedicated to that size, which was running at 100 bags/min. The other line packages 2-, 4- or 5-lb sizes, all in multiwall paper sacks.

Triple volumetric filling

Each line starts out by forming double-wall paper sacks from two separate rolls of paper, one for the printed outer ply and the other for the unprinted inner ply. The paper is cut, wrapped around a mandrel and sealed with liquid adhesive. The empty bags are then stuffed in a pocket-style conveyor that brings them to the filling section.

Filling is done via the bulk-and-dribble method. First, bags are filled with the rough amount by three in-line volumetric fillers that fill three bags simultaneously. Next, filled bags are conveyed over an integral checkweigher that checks for gross weight accuracy, feeding back over- or under-weigh information to the volumetric fillers for automatic, on-the-fly adjustment.

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Break out of the ordinary: see what’s new in packaging & processing!
Conveying Innovations Report
Editors report on distinguishing characteristics that define each new product and collected video demonstrating the equipment or materials as displayed at the show. This topical report, winnowed from nearly 300 PACK EXPO collective booth visits, represents a categorized, organized account of individual items that were selected based on whether they were deemed to be both new, and truly innovative, based on decades of combined editorial experience in experiencing and evaluating PACK EXPO products.
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Conveying Innovations Report