Carton Sealers
Trade News / January 1998MainPackaging Digest / January 1998
Dole closes produce cases without a flap! Twin random-fill case tapers use exclusive flap closing technique to effectively seal cases of Dole's citrus fruits at up to 35/minute with less waste and downtime and without flaps flying, even during long-distance export distribution. Specialized tape endures low temperature storage, high humidity and bonds well to recycled board surfaces... by Senior Editor Lauren R. Hartman Installed last spring, the two high-speed tapers were customized for Dole Central Valley's two-piece, telescoping half-slotted containers (HSCs) of Dole citrus fruit for both domestic and export sales to places such as Singapore, Malaysia and Taiwan. Equally important to the upgrade is a custom case sealing tape called Tulips Agri 25 developed by BestPack with a major proprietary tape manufacturer. The tape bands more easily to recycled-content corrugated cases, even in damp, near-freezing environments, preventing case flaps from popping open. Become Unglued The case tapers replace a laborious glue sealing arrangement more prevalent among citrus packers. No other equipment changes were required. So efficient are the machines that Dole Central Valley now saves two hours of downtime each day compared to the former equipment. Before, up to 3,400 cases were lost in waste. Plus, the company incurred higher labor and maintenance costs, the new taping machines double the output with half the personnel, according to plant general manager Donald Snapp. And, they take up 50% less floor space. "More citrus companies are moving to tapers," Snapp says, "the machines saved us a lot of overtime, downtime and maintenance because they're virtually maintenance-free. they do a better job of sealing our cases. And they're really not very expensive. Plus, they're only twelve feet long. The older machines had at least 30 feet of compression space alone. Space-wise, the new tapers are a big plus in crowded packing houses." Snapp points out that the increased capability isn't so much because the former equipment couldn't operate at high speeds. the machines ran at slower speeds, in fact, to allow the hot melt adhesive to set and band under a set of recently revised temperature conditions. At the time of Dole Central Valley's search for an improved sealing method, the company began storing the fruit at temperatures of 37 to 40 degrees F and at raised humidity levels of 98% R H, in order to maintain top quality and extend shelf life, especially of exports during the two-week or longer trip overseas. But since the corrugated shippers incorporate more recycled content board than ever, it can be difficult to keep them sealed over two to three weeks of transport, Snapp says: "The tapers are a big plus in that regard." The extended shelf life conditions proved successful at preserving the freshness of the fruit, but weren't doing justice to the glue sealing method. Sealing problems with adhesive and recycled corrugated are largely due to the shorter fibers in recycled-content board, explains BestPack's marketing V P- Pat Brennan: "The fibers are typically much shorter than fibers in virgin board and often have less adhesive bond strength, especially in high humidity conditions at cold temperatures." Flap flare-ups Previous adhesives weren't compatible with the colder, more humid conditions and would require the cases to remain longer with in the former equipment's compression belts to give the flue a chance to set. "The adhesive would often separate from the recycled-content corrugated, causing the case flaps to pop open, especially after the cases were fork lifted into trucks," Snapp says, " The adhesive would often separate form the recycled-content corrugated, causing the case flaps to pop open, especially after the cases were fork lifted into trucks," Snapp says, "The glue adhesive would often crystallized on the case at cold temperatures. Tape doesn't have the problem." Whether at the end of the packing line, in cold storage, in-transit or at the destination, the fruit occasionally fell out of the cases as flaps popped open because the adhesive would crystallize--a problem not always apparent until produce delivery. The situation adversely effected exports, which account for about 25 percent of Dole's packed citrus. At the Terra Bella packing operation, case damage was growing, and the older glue sealers were in need of replacement, as age caused heavy downtime. Overtime and extra packing personnel plus an on-site mechanic were needed in order to meet production demand. "that's no longer an issue," Snapp says. "We no longer have problems with flaps coming open, thanks to a move to taping, which was uncommon at the time." The proprietary Agri 25 clear polypropylene film tape, with its highly aggressive natural rubber adhesive formulation, solved the flap seal problem. BestPack discovered the tape adhesive from its use in agricultural applications. Provided on 1,000-yd rolls three inches wide, the 2.4-mil tape's high tack formula was designed to bond in harsh environments--including damp, cold temperatures-- which allows it to easily bond to the shorter fibers of the recycled corrugated shipper substrate. The tape is also thicker than conventional1.8- and 2-mil sealing tapes, BestPack's Brennan tells PD, so is stronger and more durable. Case size flexibility The new tapers are also specifically designed to the seal the two-piece HSCs smoothly and automatically, compared with other sealers designed for regular slotted containers (RSC's) more commonly used in other industries. "The two-piece HSC is more prevalent in citrus applications than any other container," Brennan says. "since the closures on the two case styles are similar, many citrus packers simply use automatic gluers and have someone manually position the top half of their cases in the seal area of the machine." A labor-intensive process indeed, Snapp remembers. In Dole Central valley's situation, the former equipment wasn't as versatile or as adjustable. "Sometimes the manual feeding or positioning would risk damaging the cases," Snapp says. Dole Central Valley uses four case configurations, depending on the fruit and destination, so personnel appreciate the new case sealing equipment's versatility, Snapp affirms. Approximately 90% of the company's domestic oranges are cased in telescoping shippers and top measurements from 16 3/4 X 11 1/16 X 5 13/16 to 16 13/16 X 11 1/8 X 10 3/8 in. The two-piece telescoping HSCs for cross-country domestic shipments generally hold 43 to 45 pounds (or 88 pieces of fruit) and are made by Weyerhaeuser, Cases includes a 200# - test, C-flute corrugated outer sleeve, die-cut with circular vent holes. Many of the outer sleeves feature full-color 42# preprinted liners with a 33# medium and 42# kraft inside liner. Graphics avary depending on customer and grower. Inner sleeves are made of 250#-test, C-flute natural kraft corrugated, post-printed flexo in black. Export cases, also from Weyerhaeuser, contain 50 to 52 pounds of fruit and are two to three inches taller than domestic cases. Able to seal containers from 16 to 20 inches in length, 10.5 to 15 3/10 inches in width and 5 1/2 to 14 1/2 inches in height, the 5FAMS-FB2 tapers at Dole Central Valley's plant average 35 cases per minute. With six upper side compression rollers, interlocking gates, adjustable bed height and two back minor flap folders capable of handling flaps folded back parallel to the conveyor bed, each new taper ensures smooth performance without operator intervention. "We needed the the machines' flexibility of handling different case sizes and case height," Snapp says. The taping system incorporates two back minor flap folders specifically designed for HSC telescoping cases. Capable of handling flaps folded back parallel to its conveyor, the machinery incorporates three separate drives for durability. A final closing station seals top and bottom flaps of the container without tabbing the flaps together. This prevents taping top and bottom halves of the cases together. Patented three-inch taping heads seal up to 2,300 cases per hour. Side sweeper benefit Cases are erected by hand and pattern-packed either manually on one of 22 assembly lines or automatically on one of nine production lines equipped with citrus industry-built pattern packers. The manually erected top half of each case is positioned over the filled base as cases convey to the continuous-motion taping machines and index to the "shaking/lifting" station on live roller conveyors. A positive lifter station with a shaker device shimmies the tope half of the two-piece case during the lifting process so that the top flaps are property positioned before the case enters the flap-folding station. The flaps of the top half of the case are open. Flaps on the bottom half have already been folded in. Side lifters raise the top half of the case away from the base for folding of minor flaps as the container travels through the machine. Throughout the process, the case is kept property positioned and the inner sleeve remains stationary for consistent closing and sealing. Next, major flaps of the caser's top half are spread outwards by overhead chrome folding guides, creating an opportunity for the side lifter to hold the top half up. Minor flaps are next folded and tucked in by a sweeper arm; the folding guides bend flaps at the score line before a trough-like device that, with an additional set of chrome guides, folds the major flaps closed. Extended guide rails keep the outer sleeve in the "up" position, to prevent taping of the two halves of the case together. Six adjustable rollers then compress the container as the case contacts top and bottom taping heads. The heads apply the aggressive tape down the center of the container where the major flaps meet. The outer sleeve then lowers and the case is ejected for manual palletizing. "Dole's input was vital to us in refining the machine's design to work more efficiently and smoothly for them and the citrus industry in general," notes BestPack's Brennan. "The standard way is to have a back kicker come straight down and tuck in the flaps," Brennan explains. "The new kicker effectively sweeps the flap from the side so that it hits a large target area, providing more consistency in lifting the tope of the case. Otherwise, if the back flap is leaning, it could be missed and the box could be sealed with a flap hanging out. By sweeping it from the side, the flap is caught and folded so the failure rate was all but eliminated." In addition, the taper is flexible enough to compensate for differences in fruit size, Brennan says, Regardless of the crop size, a specific number of fruit has to go in each case, which means the machine has to compensate for potentially bulging cases." Here is where the lifters benefit the system and minimize the need for a lot of moving parts in the machine's taping section, Brennan points out. "No one in the citrus industry was taping cases until recently because no one could really come up witha better mousetrap. It soon became evident to us the t eh growth in citrus packing was tremendous. So we felt we had to develop a taping machine that could work to accommodate two-piece cases." BestPack modified their taper in the way it folds of the outer sleeve as the case moves through the machine. Fruit-friendly "We also had to make sure our taping machine was flexible enough to work with either automatic or manual case packers," he says. "A case packed by a person can be oriented differently, as far as the flaps are concerned, than an automatically packed case, so we kept running into challenges as we developed the system for citrus packers." Snapp, who finds and works with the citrus growers' pool and manages the citrus packing operation at Terra Bella and nearby citrus growing sites, says the compact tapers operate at nearly twice the rate of the former equipment, with far less maintenance. Line operators find the tapers more easily accessible he notes: "It's a welcome change and a great machine. And the tapers are fruit-friendly because we see less damage." So convinced is Dole Central Valley that it made the right decision to move to taping its cases that the company installed two additional systems in November '97 at another Dole packing operation in Redlands, Calif. More information is available: Case tapers, sealing tape- BestPack Packing Systems, 10676 Fulton Court Rancho Cucamonga, Calif. 91730
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