Rollers stabilize stretch wrapping

When it comes to stretch wrapping equipment, packagers and manufacturers alike concern themselves with specifications such as the number of loads that can be wrapped per hour, the size of load the machine will handle, its ability to prestretch film to minimize material usage, and so forth. Yet the internal components that make such efficiencies possible often go unnoticed. That's not the case for Lantech, the Louisville, KY-based maker of a variety of stretch-wrapping machines. Recently, the company switched to film carriage guide rollers provided by Efson (Wilmington, NC) for its Q-Series and S-Series(TM) Straddle semi-automatic stretch wrappers. The rollers measure approximately 3" wide, with a 2 3/4" diameter. The injection-molded, fiberglass-reinforced nylon rollers are used to smoothly raise and lower the machine's film carriage. In the tower-like Q-Series, for example, the rollers are used in at least 10 model variations, according to Bob Denley, Lantech's director of mechanical engineering, research & development. During the wrapping process, the film carriage, located on the machine's exterior, moves up and down to deliver film to the pallet load, which rotates on a nearby turntable. The movement of the film carriage is computer controlled, using a variable-speed motor and high-torque belts. These components allow the carriage to ascend and descend along two structural steel posts, located within the machine. Two rollers are positioned on each post, directly across from one another. The entire component assembly makes for free rolling movement, eliminating friction between the film carriage and posts during stretch wrapping. "These rollers replaced other rollers that we had used," explains Denley. "We made the switch for different reasons. Cost was one issue. Our manufacturing process was another. In the past we ordered components in batch quantities, often with quarterly deliveries. Now we work on a just-in-time basis, so component delivery is critical. We get deliveries on a weekly basis and operate via a partnering process with our vendors that's based on a system used by Toyota. We make commitments in terms of delivery volumes so the vendors can judge material expectations." Lantech is more than pleased with the performance of the new rollers. "By providing variable-speed control of the film carriage, the top and bottom of every pallet load has the desired number of wrap layers strategically placed to contain and stabilize the load," says DeAnna Dessify, Q-Series marketing manager. "The guide rollers allow the carriage to accurately follow computer program directions, unhindered by friction. "We originally tried flat belt urethane rollers, but surface contact between the rollers and the tube was not adequate to provide the needed carriage stability." Ultra high molecular weight polyethylene was also considered, but deemed cost-prohibitive. "The injection-molded nylon guide rollers assure straight-line vertical travel of the stretch wrap film," Dessify notes. "Accurate vertical travel of the film as it serpentines around a rotating pallet load is crucial to securing and protecting the load. The friction-free roll carriage helps our machines attain high quality, stable loads." Farley favors rollers The ultimate judge of any packaging machine, however, is the packager who uses it. Unhappy with the efficiency of an earlier stretch wrapper, Chicago-based Farley Candy purchased a Q-Series stretch wrapper in July to wrap a variety of its unitized loads of candy. Farley bought the machine through its local distributor Zellerbach (Miamisburg, OH). Positioned within a warehouse at its Melrose Park, IL, plant, the Lantech wrapper has greatly improved Farley's wrapping operation. "This unit is built better, it can take much more of a pounding, and it operates faster," says Roger Ninneman, Farley's assistant director of manufacturing. "We run the machine five days a week, on two daily 12-hour shifts, and another eight-hour shift on Saturdays. The machine has the flexibility to provide more or less wraps around the top, center, or bottom of a load, something we couldn't do before. These guide rollers become critical in this process." At the warehouse, operators bring each load to the wrapper. Once the load is on the turntable, a Farley operator pulls the leading edge of the film and attaches it securely to the load by tucking in an end between the pallet and outer row of product. Then, the operator presses the start switch. A built-in, reduced tension start control delays stretch tension until the film is secure. The wrapping then commences, with the rollers moving the film carriage up and down for the wrapping cycle. He notes that the wrapper is set to provide a 200% prestretch for the 60-gauge low-density polyethylene film he uses. The film comes in 20" web widths, from various suppliers, and is also purchased through Zellerbach. The wrapping system includes a ramp that allows entrance of a fork lift onto the turntable. "This is a major advantage for us," Ninneman points out. "It's superior to anything else on the market. We can drive the forklift right onto the turntable, set down the load, pull out the fork lift, let the machine wrap the load, then drive the forklift back onto the turntable to pick up the wrapped load. It's a very efficient process now."