How to Choose the Best Stretch Film for the Job
It unites—assembles products into one unit—usually on pallets—which makes packaging and shipping efficient and cost-effective. Product bundling reduces handling costs and saves time. This ensures a more secure and efficient distribution process, while protecting the product from damage and theft. Applying stretch film is one of the most common and safest methods of achieving this.
The goal of choosing the best stretch film is to find one that fits your company’s specific needs without paying for unneeded property. For example, a load that will spend most of its time in a warehouse or shipping container, does not require a UV protective film. On the other hand, a load with a light film that does not fit into the corner of the pallet will experience film leakage and load displacement. But if you’ve never used stretch film before or aren’t satisfied with the film you’re using, how do you know which one is the right one? Here are 6 considerations for choosing the best stretch film for the job.
Main Cost Comparison: Price/lb. vs. Price/ft. vs. Price/load
When talking to stretch film sellers, trying to figure out how their product compares to the product consumers are currently using can be confusing. All films are sold in pounds. Traditional film, which is usually taller in size, is actually cheaper per pound because it uses less expensive plastic resin to make the film.
High performance films are more expensive because they are produced with better quality resin and can be layered. This is a more expensive manufacturing process. High-performance film generally ends up costing less overall because the lighter weight of the film offsets the higher price-per-pound
However, what really matters to the consumer is how much the film costs per foot. Even more important than the cost per foot is the cost per load wrapped. The argument for newer high-performance films is that while they are expensive (more expensive per pound), they are much lighter and therefore lighter.
For example, a high-performance film designed to replace traditional 80-gauge film may be 20% more expensive to produce, but may require 50% less film to withstand loads because it performs as well as 50% thicker material. . The end result in this example is the user saves 30% on film costs by switching to thinner high performance films.
To properly analyze the price savings, pack two loads. Then cut the film from both loads and weigh on a small sensitive scale. This will show the amount of film used for each load. Then multiply the weight of the film by the price per pound (ask your seller about the weight of the roll or the weight of the box if it’s not clearly marked) and divide by the price of the roll or box. This will produce a price per load. Multiply the price per load by the usual number of loads for each day, every week, and so on.
Since there are so many variables with movies, users have to be very careful to understand and confirm the math itself and not rely on the salesman’s math. Part of the process should always be to adequately sample new material before accepting any changes. The bottom line is that new material must be loaded as safely and effectively as old material. Here are four additional considerations for choosing stretch film.
1. Standard or High Performance
This is the most important decision. Most decisions will be based on price, but will need to be tailored to the requirements of the job. Not so long ago, before the advent of highly innovative stretch films, size (thickness) was the only thing that mattered. Well, that’s just one of many considerations.
Standard/true-gauge stretch film offers plenty of stretch, tear resistance, and strength. The main drawback is wastage, as it is impossible for the average worker to apply sufficient force to reach the film’s maximum stretching potential.
Economical/micron strain films are a step back from properly measured strain films and often come in sizes 57, 60, or 63. The main differences are thickness and amount of strain potential. It is often stiffer and will not stretch as much as properly measured film. On the other hand, it is robust, more affordable, and can produce less waste.
Hybrid/multilayer stretch films are usually used instead of lighter gauge films. It is produced in 47, 51, and 53 gauges. It has more layers, is stiffer and has less tear resistance than micron stretch film. Benefits include: lower costs
highly elastic film recovery, high strength formulation and film neck reduction. In the high performance category, even light film gauges have higher tear and puncture resistance, and excellent adhesive properties.
But if one or a combination of these conditions exist, the heavier (more expensive) traditional film will be a better choice and will save you money in the long run (less risk of worker injury and load damage). Traditional films are considered very easy and often result in fewer complaints from the warehouse. Application accuracy is not critical as film weight can help compensate for poor application by workers.
Carefully consider the type of load and even the skill level of the warehouse staff. In general, in a well-controlled environment with a good diced load, a cheaper, high-performance film will save money.
2. Hand Film or Machine Film
Handheld dispensers can be as cheap as a few dollars while fully automatic wrappers run up to 1,000 dollars. A general rule of thumb is that if consumers are packing 15 or more loads per day, it is more cost-effective to machine than to wrap by hand. At that level the machines justify their costs by reducing the cost of manual labor and the possibility of injury.
Despite productivity and liability concerns, most machines pull at least 200% stretch wrap before applying it to a load. This results in legitimate savings of up to 50% of the cost of the film. A company that has historically used a full pallet of hand film each month could reduce its use to 6 pallets per year. These film savings can pay off equipment very quickly. In addition, machine-wrapped loads are generally safer than hand-wrapped loads. When the stretch film is applied by the machine:
• Production rate increased
• Labor costs decreased
• Fewer injuries
• The packaging is consistent
• There is better quality control
• Less film is used because the film is stretched properly
So for a company that handles 15 or more loads per day, a stretch wrap machine will pay more than itself. The following is a summary of hand and machine options.
Manual / Hand Wrap
• Extended Core: The expanded core film creates a natural grip for the wrapper. This is a very economical option as it does not require any equipment. The downside is that it provides little control over the stretch and is difficult in the hands of the worker.
• Mechanical Brake/Pole Wrapping: The rigid structure supports the film core while the mechanical brake system provides the resistance needed to stretch the film. Pole wraps are similar, except the coils are at the ends of the extended posts. This reduces the need for workers to bend and reach during application.
• Wrap Turntable: The load rests on the turntable which rotates the load. The film roll automatically moves up and down according to the wrapping. Stretching is controlled by load rotation speed and/or built-in pre-stretch feature.
• Orbital Wrapping: The film is located in a carriage placed on a vertical ring. The load is fed horizontally (or vertically in the case of a horizontal ring system) through the center of the rotating ring as the film is applied.
• Rotary Arm Wrapper: The load remains motionless as the rotating arm rotates around it, wrapping the load. This type of wrapping is best for light loads or those requiring high rotational speeds which can cause the load to become unstable.
Automatic wrappers are similar to semi-automatic wrappers except that they include a conveyor system for automatic loading. Equipment also applies, seals, and cuts films.
3. Blown Film or Cast Film
There are two basic methods of making stretch film — blown and cast. The manufacturing process determines the properties of the film.
Blown film is produced using a blown film extrusion process. The resin is melted, blown in giant bubbles and cooled with air. This is a slower (more expensive) process but results in higher quality. Its characteristics are: superior strength, stretch, film memory and puncture resistance; but poor clarity and very noisy while relaxing. It has superior strength to accommodate irregular loads.
Cast film is produced using a cast extrusion process. Instead of being air-cooled, the film is passed over cooling rollers. This makes the cooling process faster and the product cheaper, but also inferior to blown in many important respects, including strength and stretch. Distinctive characteristics of cast strain films are: clarity, high gloss, quiet release, adhesion and consistent thickness
newer high performance cast films can be stretched up to 300%.
• Movie Memory: Blown has better movie memory (shrinks back to its original size better after being stretched). Cast has less memory (this causes the load to shift).
• Load Retention: Blown holds better and won’t stretch once applied. While the cast holds loads well, it will stretch once it is applied to the pallet (this also causes load transfer).
• Puncture Resistant: Blown is much more puncture resistant than cast, which will generally tear if too much pressure is applied. Blown is more forgiving around sharp edges.
• Visual Clarity: Blown is not crystal clear. This can make reading and scanning more difficult, but helps reduce distracting glare. Clear cast; makes reading and scanning under ordinary warehouse lighting easy.
• Rewind Noise: Hits tend to be very hard when released from the reels. Cast is barely noisy.
• Film Cling: Blown has one-sided cling-this creates higher load retention. Cast has natural adhesion on both sides. This can make the pallets stick together. However, cast films can be produced with one-sided adhesion.
Due to the lower strength and memory of the film, casts are best for lighter loads with standard forms. It also tends to be less expensive than blown—which makes it a good choice for less demanding high-production applications.
4. Standard or Pre-Stretch
The pre-stretched film is stretched near the final breaking point at the mill and then rolled into rolls. This means it does not require as much physical energy as standard stretch film. This is the main reason why pre-strain films are popular for hand wrapping. In fact, hand-applied pre-stretch films can create the same load stability as machine applications. The reels are also light and easy to handle and can be applied with a forward wrapping technique, which helps prevent slip and fall incidents. Essentially, users get the same (or better) load stability with less product, less physical energy, and more control.
While pre-stretched film is more expensive per foot than traditional film, it requires about half the amount of film, which can create net cost savings (much lighter and therefore cheaper per pound). Another plus is that the pre-stretched film will naturally tighten after application. The unique memory of films and their tendency to tighten after application is the most important reason for pre-stretched films.
The jobs that make the most sense for pre-stretched film are those that require hand application—especially where the worker does not have the strength to handle or tighten traditional film and/or where the worker is handling irregularly shaped loads. Previously stretched films should be used for loads no heavier than 1,200 pounds, as they are usually stretched too thin to withstand heavier loads. It can be applied either by hand or by automatic machine. Companies that position themselves as green can make a good reason to use pre-strain film because it requires less product.
In addition to the 4 considerations mentioned above, there are special qualities that are very beneficial for some applications:
• Ventilated: Typical applications include anything that requires heat and humidity to circulate air to prevent spoilage, such as produce and other food products.
• Color/Print: Using stretch film in multiple colors or printed, makes it easy to identify product and spot faults. It’s also great for product coding and dating.
• Bundling Film: These come in 2″, 3″, and 5″ widths and replace tape and string. This has the advantage of not leaving a sticky residue or string marks. Best for packing small items together.
• VCI: Vapor corrosion-inhibiting stretch film blocks moisture and contaminants, preventing rust and corrosion. This is especially good for products that come into contact with water and other rust/corrosion-causing substances – including rain and saltwater vapor which are common near seaside piers.
• UVI: Users who store pallets loaded outside for extended periods of time will need an ultraviolet barrier film. However, UVI films vary in how long they will provide protection before the UV properties begin to diminish (usually 3-12 months).
By now you should be pretty sure what you need, but might need a little confirmation. Where can you get unbiased advice? Look for industrial packaging suppliers who have been in this business for a long time