Stretch Film 101

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Workers unloading rolls of stretch film

Using stretch film to wrap your pallets is the most popular packaging method. Stretch filmoffers protection from weather and debris and is cost effective, recyclable, and adaptable to almost any load. Previously we have discussed the simple differences between stretch film and shrink wrap, but there is more than meets the eye to this highly stretchable plastic film. As mentioned before, stretch film is used to tightly wrap products as one on pallets for shipment or storage. We will be discussing three very common types of this film along with how to successfully secure and wrap a pallet.

The first and most cost effective stretch film is cast film. It is manufactured using a cast extrusion process; the thermoplastic material is melted and extruded through a flat die onto a chill roll, where it is quenched and re-solidified. Cast stretch film offers excellent clarity, reduces the force required to stretch, and increases tear resistance. Great advantages of this film are its low cost and superior cling (the double-sided cling provides additional security). However, it does not offer the load or holding power of other films nor the same amount of memory. The bottom line: if you’re looking for a low-cost stretch film that still ensures security and keeps your items tightly bound, cast film is the perfect fit.

Next is blown stretch film, which is manufactured using a blown extrusion process. Plastic melt is extruded through an annular slit die (usually vertically) to form a thin-walled tube. Air is then added via a hole in the center to blow up like a balloon while and air ring blows onto the film to cool it. Blown stretch film offers many benefits cast film does not. It is a higher quality film and it is equipped with a higher load capacity, stretch capacity, and degree of memory. Due to all its perks, the cost of blown stretch film is higher than other films. This film does have poor clarity due to crystallization in the manufacturing process.

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Blown stretch film in the manufacturing process

The third film we will compare is opaque stretch film. This is more of a specialty film used with valuable shipments to detour pilferage by completely masking the products. Since it offers a sturdier security shield, it helps protect packages from UV rays and prevents potential rain, dew, and dust damage. Opaque stretch film is available in a variety of colors and outlasts regular clear film during extended outdoor storage. Whether you need to protect expensive shipments or color-code a number of packages, opaque stretch film will do the job.

Once you’ve decided on which stretch film you will need, it is imperative to know how to secure the items on the pallet properly. Follow these steps and you will have a beautifully wrapped pallet so tight your packages won’t even dream of escaping!

1. Cut about 1 yard off the roll and squeeze 8-10” of the end together to form a rope.

2. Thread the rope through one corner of the pallet.

3. Begin around the base, wrapping the stretch film around approximately 5 times while keeping the film tight.

4. Slowly work your way up the box, focusing on keeping the wrap snug.

5. Once you have reached the top, push the top boxes to see if they move. If they shift at all, wrap your way down to the bottom of the pallet.

6. If your package does not move at all, you have successfully wrapped your pallet and do not have to worry about your shipment shifting in transit!

Getting the Most From Your Stretch Film

stretch filmAs shippers focus on taking costs out of their supply chains and reducing the amount of material that goes to the landfill, they are also taking packaging material out of their loads. “The corrugated is thinner, we’re taking product out of cases and putting it in trays, or in some cases, the primary package is now supporting the load,” says Jim Lancaster, president and CEO of Lantech, the maker of stretch film systems. “At the same time, they’re not thinking about the secondary package, such as the stretch wrap. That’s when they end up with damage.” Lancaster says shippers can no longer look at just their pallet – or the stretch film going on their load – in isolation. They have to understand the eco-system in which the unit load will operate, and the biggest impact on that today is sustainability. Paper towels and bottled water are two examples of products whose shipping methods have been modified to fit this sustainable mold. They both used to be shipped in cartons and now they’re just stretch-wrapped to a pallet. Bottled water has especially been affected by this change; the bottles themselves are manufactured from a thinner gauge plastic and are assembled with smaller screw tops.

So how do you wrap a load so that it arrives at its destination in the same way it left the factory? Here are several tips Lancaster shared that Lantech defines as lean wrap:

Focus on containment force, not the gauge of the stretch film: Containment force is a function of the amount of force applied as the load is rotated and the number of layers of film. (Ten wraps of a thick film provide the same containment force as 20 wraps of a proportionately thinner film if both are applied with the same force.)

Create a uniform wrap: Some customers mistakenly believe that putting more film at the top and bottom of the loads, then skimping in the middle will hold an unstable or top heavy load in place. As packaging moves in moving trucks, the stretch film shifts from vibration, exposing the weakest point and causing the seal to fail. For this reason, Lancaster suggests that shippers uniformly distribute the film around the load.

Tuck in your tails: Have you ever tripped over your own untied shoelaces? There’s a similar consequence when it comes to stretch film, which is the tail of film that’s left after wrapping a load. Make sure then that you tuck in your tail. Not only does this not look professional, but the tail can get stuck under a forklift or in a conveyor roller and cause your package serious damage.

Attach the unit load to the pallet: If the stretch film does not lock the load to the pallet, it can vibrate off the edge. Past incline tests show that when the bottom 20% to 30% of the web of film is rolled into a cable just above the fork opening, there is a dramatic improvement in load performance.

Although it is important for a company to practice eco-friendly measures, it is also imperative not to skimp out on important packaging procedures for the sake of its sustainability goals. In the end, if your package is not delivered in one piece, your customers are not going to care if you are an environmentally friendly business or not.