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Article | August 20, 2013
Alternatives to spiral stretch wrapping
Insights from the updated 2013 End-of-line Packaging Equipment Playbook...
Stretch wrapping is a popular method of unitizing cases or bags for shipment. However, it is not the only choice. Making the right choice of pallet packaging method involves a thorough analysis of many parameters that influence not only the daily operating costs, but also the entire distribution chain performance. Cost-effective alternatives can wring significant savings out of end-of-line operations. When product leaves the production facility, it is at its highest value-added state, and ideally should arrive at the customer’s facility in the same condition.
In addition to manual strapping and banding, here are some other automated or semi- automated alternatives to stretch wrapping worth considering:
A water-based cohesive/adhesive is sprayed onto boxes or bags and keeps them in place without wrap, corner protectors, or tear sheets. The material exhibits very high shear strength, yet when pulled straight up, pieces easily come apart again. The ideal application for this approach is boxes or industrial bags for food, beverages, chemicals, and edible animal feed. Four reasons to consider this method over stretch wrap:
• Reduced materials costs, by getting rid of wrap, corners, and slip sheets.
• Sustainability: spray is organic and has no effect on recyclability of bags or boxes.
• Even packagers who must use stretch wrap, per the requirements of retail customers such as Walmart and Costco, can reduce their film use by up to 60% and add stability by spraying the pallet load first. Even with the added costs of the adhesive and applicator, the net overall spend is less, according to cohesive suppliers.
Introduced in the late 1980s, the stretch-hooding method of pallet packaging is suitable not only for bagged products, but also for products in bins, cases, pails, and other primary packaging formats. Domestically available coextruded stretch-hood films allows for prestretch percentages exceeding 80%, providing materially improved film yields than were possible even a few years ago. This performance, combined with film thickness reduction down to 1.6 mils, means that the per-pallet film cost with stretch hooding is extremely competitive with that of spiral stretch wrapping. Advantages include:
• The height of the pallet load is measured automatically as the pallet enters the machine, ensuring that only the amount of film required for the application is dispensed.
• Energy consumption is low since the film is not heated, and available servo-drive technology further reduces energy and maintenance costs, while helping to drop noise levels.
• For products sold at retail outlets, such as home centers, the clear, one-layer stretch- hood film provides much better product recognition at point-of-sale than multilayer spiral stretch-wrap film does. It is also possible to print advertising or handling instructions on the film.
• Stretch hood film allows for easy bar-code scanning, virtually eliminating misreads.
• Stretch hood film consistently maintains its tension, and is particularly well suited to products that, due to their physical properties, tend to settle after being bagged and palletized.
• Stretch hooding represents the least labor-intensive method of pallet packaging. The film roll can be up to 39 in. in diameter, allowing for 10 times-longer film- change intervals. The film roll is handled by forklift, but the roll change is a very simple procedure, typically taking no more than 10 minutes.
• Stretch hooding provides tamper-evidence. It is impossible to remove an item from the pallet without destroying the film. This means that it can easily be established if the pallet load has been tampered with.
• Stretch-hood film is fully recyclable.
• Stretch hooding works well for irregularly shaped pallet loads as opposed to stretch wrapping where the top sheet can be displaced or slide off during conveying or wrapping.
Shrink hooding A space-saving, compact shrink-wrap machine combines hood application and shrinkage in one operation, and can package up to 100 pallets per hour. The machine head can be lowered to ground level, simplifying maintenance. Pallet- sized systems feature pallets or single products passing through a film curtain, which packages different pallet or product formats at up to 130 pallets, or 400 product pieces (domestic appliances, for example), respectively, per hour. Advantages include:
• Low energy consumption and great packaging flexibility in pallet shrink wrapping.
• Recent improvements all but eliminate fusing of the shrink film to the PE-packed product beneath it, as well as creasing of the film.
• Available undershrink system adapts itself automatically to the pallet contour in order to ensure secure freeing of the pallet. The undershrink is carried out well under the runners of the pallet—an essential precondition for optimum load stability and the use of thin film.
• Surface of the film after shrinking is high quality, permitting an optimum display. Bar codes under the film can be read without any problem.
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