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Carton producer stretches savings

Paper company Rock-Tenn switches from a shrink wrapping system to a customized stretch wrapper to unitize skids of paper. Benefits stretch beyond expectations.
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FILED IN:  Machinery  > Labeling
     

Most people in the packaging business know Rock-Tenn as a packaging supplier. But this Norcross GA-based paper products vendor becomes a packager when it comes to getting its products to market. Take for instance boxboard which Rock-Tenn sends to converters who produce folding cartons for any number of applications including many in the food industry. Although it may vary from day to day Rock-Tenn's Minneapolis MN plant produces and packages about 3 skids of board per month. About a year ago the company replaced its old shrink wrapping system with two Sidewinder 6 Wrap and Weigh stretch wrapping systems from Infra Pak (Farmer's Branch TX). Purchased through local distributor River City Packaging (Minneapolis MN) the machines have cut Rock-Tenn's material costs in half and have netted a significant savings in operating expenses. Jerry Krogh shipping superintendent at Rock-Tenn's Minneapolis plant recalls the old system: "We shrink-wrapped everything. The equipment was expensive to operate. There was a gas oven and you had to keep temperatures even at 400 degrees [Fahrenheit]. Every time the oven doors opened the temperature would drop. It was probably the size of a single-car garage so you can imagine how much heat would escape." Rock-Tenn's largest load says Krogh measured 80" long x 52" wide and weighed roughly 6 lb. Cycle time was slow requiring about 40 seconds in the oven 35 seconds to cool and approximately another 15 seconds to convey through the oven he continues. The 20-year-old system also required a lot of maintenance and it accepted only customized shrink bags made of a 4-mil plastic blend in many sizes to accommodate the varying load sizes. "The bags were expensive to order...and miserable to keep track of" says Krogh. Rock-Tenn's decision to use the Infra Pak/River City system at the Minneapolis plant was based partly on familiarity. "Number one River City is local" says Krogh. "And we'd seen the Infra Pak name in trade magazines." Krogh was also familiar with some of the anticipated benefits of the Sidewinder 6 system: increased warehouse space less energy expended less downtime and materials savings. Custom configuration Equally important to Rock-Tenn was Infra Pak's willingness to customize the stretch wrappers in order to bring some new benefits to the line. Scales for example have been integrated into the system as well as an automatic carriage return for stretch wrapping. Before stretch wrapping begins sheets are stacked on skids. These are moved by an electric pallet jack to the platform of the Infra Pak system which contains the turntable and integrated scales. While in the past says Krogh skids of paper were carried to a scale and then to a platform that fed into the shrink wrapping machine the new system allows weighing on the spot. "We had scales built into the stretch wrapper so it eliminates that step" he says. "We wanted to handle the loads as little as possible." Weights are viewed through a digital display for count verification and print-and-apply shipping labels are produced at this time so that operators can apply them after stretch wrapping. Next the leading edge of the stretch wrap is tucked into the load. The turntable inside the Sidewinder platform rotates the entire skid allowing the skid to be wrapped in stretch film. A pre-stretch device maximizes use of the material. With the new system "we're probably saving a minute a load" says Krogh. "And take that times 100 loads a day...it frees up our operators to do other things and help out in other areas. "We'd looked at several kinds of stretch wrapping systems and one of the things we noticed was that after wrapping the carriages would end up on the bottom" says Krogh. He didn't like this because it meant operators would have to bend continually. "We do about 3 loads a month so we wanted to eliminate as much [operator] bending as we could. "Infra Pak was able to make the carriage stop where we wanted it to. It finishes at the bottom but then it returns 'home'-and we can program the wrapper so that it returns to a 'home' position that we want." In switching from the custom shrink bags to stretch wrap alone Rock-Tenn was able to cut its materials costs in half. "The bags would cost anywhere from $1.40 to $1.70 each" Krogh states. "Now stretch wrapping a load costs 75 cents at the most." Rock-Tenn uses an 80-ga linear low-density polyethylene stretch film from Paragon Films (Broken Arrow OK) also purchased through River City. The stretch film has saved Rock-Tenn about $19 a year compared to shrink bags says Krogh. Krogh estimated that Rock-Tenn would save another $10 a year in energy costs. That figure turned out to be $18 per year. All in all says Krogh pay-off on the whole system will take less than 21/2 years. "It's been remarkably trouble-free" notes Krogh.

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