by Sterling Anthony, CPP, expert witness, packaging, warnings, patent infringement, cargo loading & securement, insurance claims
Stretch-wrapping is the most common method for unitizing cargo onto a platform, typically a pallet. The method involves the tight application of plastic film, in overlapping layers, around the cargo, such that the cargo is held together as a unit that can be handled mechanically. Application can be done manually; however, at modest-to-high production rates, only application by machinery is practical.
Multiple factors play into the proper choice of stretch-wrap, chief among them: manufacturing method, thickness, toughness, aesthetics, and, of course, stretch characteristics. The proper choice, therefore, is application-specific, matching the film to the requirements that the film must fulfill. Another way of stating it is that the film must maintain load integrity (keep the load intact) until intentionally removed at the point of destination.
Throughout its movements in the stream of commerce, a stretched-wrapped load will encounter a variety of forces, induced by the activities of transportation, materials-handling, and storage. The forces are vibration, shock, and compression, and, whether singularly or in combination, can cause stretch-wrap to fail. The result is a load that can shift and even collapse.
Stretch-wrap never is the sole guarantor of load integrity; rather, it is a vital component of a system, which includes the aforementioned activities of transportation, materials-handling, and storage. Stretch-wrapped cargo should be loaded and secured within a transportation vehicle in a manner that renders the cargo immobile throughout transit. Stretch-wrapped cargo should be mechanically handled (by forklift, for example) in a manner that serves to keep the load intact. Stretch-wrapped cargo should be stored in a manner that serves to keep the load intact.
There are forces inherent in transportation, materials-handling, and storage that never can be eliminated, but, nonetheless, can be held within manageable limits. When that’s done, yet load integrity is compromised, it’s justified to investigate stretch-wrap as the possible weak component of the system. That’s because a properly stretch-wrapped load should withstand the forces under all reasonably foreseeable conditions.
Mention should be made of the role of stretch-wrapping machinery. The machinery not only should undergo scheduled maintenance but also should undergo daily calibration checks to assure that it’s operating within specified tolerances. In the absence of such Quality Assurance methods, loads can be stretch-wrapped with insufficient tension, among other negative results.
When stretch-wrap fails due to inadequacies in material or machinery, compromised load integrity is a predictable result. When it leads to damage to cargo or injury to people and litigation ensues, the parties would be wise to retain an expert.
The expert should have knowledge, experience, and training in the specifying and procurement of stretch-wrap and stretch-wrapping machinery, in addition to how they are mated for optimal results.
Sterling Anthony, CPP, is a consultant to the industrial, institutional, and government sectors and an expert who provides services to the legal community. He is a former manager at Fortune 100 companies and a former instructor at two major universities. His contact information is: 100 Renaissance Center-Box 43176, Detroit, MI 48243; (office) 313-531-1875; (cell) 313-623-0522; (fax) 313-531-1972; thepackagingexpertwitness@gmail; www.thepackagingexpertwitness.com