Stretch wrapping is a simple and effective solution for palletizing boxes, securing loads and bundling loose items. But what kind of stretch film is best for your application? With all of the options out there, things can get confusing! Here's a guide to some common stretch wrap terms and how to choose the right stretch film for your needs.
Machine Stretch Film vs. Hand Wrap
The first question is easy: how will you be applying your stretch wrap? Stretch film comes in both machine and hand grades.
Hand stretch wrapping is done manually by simply winding the stretch film around the objects to be wrapped. Proper tension must be used to ensure a tight wrap and secure hold. Hand stretch film is designed for the job, with shorter, lighter rolls that can be comfortably applied by a human.
Machine stretch wrapping is fast, easy and efficient. Machine wrapping can also reduce waste and provide a tighter and more consistent wrap for maximum load security. Stretch wrap machines may be fully automatic or semi-automatic. When machine wrapping, you must use a stretch film made for the job.
The biggest difference between the two is in the stretch rate of the film, or the amount that the film can stretch before tearing. A film with a 100% stretch rate can double in length without tearing. Higher stretch rates result in less waste (you can wrap more with less film), lower costs and better tension. Hand film stretch rates are typically in the 75% to 150% range. Machine film stretch rates can be as high as 200%-250% or beyond. The higher the yield, the more you get for your money.
Stretch Wrap Gauge
The second consideration is the thickness, or gauge, of the stretch film. Both hand and machine films come in a range of gauges. The gauge of a film can be converted into mils or microns; 50-gauge film is .5 mil or 12.5 microns thick, while 100-gauge film is 1.0 mil or 25 microns thick. Stretch film is available in gauges ranging from 37 to 150.
The thicker the gauge, the more resistant it is to tearing or puncturing and the more weight it is rated to hold. For example, a standard 80-gauge stretch wrap is rated for loads up to 2,400 pounds.
Heavier gauges require more tension to apply. They also are more costly. Picking the right gauge for your application will ensure a secure load without adding unnecessary costs.
Blown vs. Cast Film
When shopping for stretch wrap, you may run across the terms "blown" vs. "cast." These descriptors refer to the way the film is made—and yes, they matter. Blown and cast stretch films have different properties, strengths and weaknesses.
Cast stretch film is created by extruding a polymer resin through rollers. This is a newer manufacturing method that is highly controllable and economical, resulting in a film that is higher performance and more cost effective for many applications. They are also generally clearer and shinier when applied to the load, unwind quietly and resist tear propagation. Cast films make up roughly 75% of the stretch wrap market.
Blown films are made by blowing a large bubble of air into the hot resin as it emerges from the extruder. The film is pulled off the bubble and into rollers as it cools. Blown films are more expensive, but they have advantages for applications requiring extra load stabilization or durability. Compared to cast stretch film of the same gauge, blown films are more puncture and tear resistant, have higher levels of cling and are extremely stretchy. That extra clinginess has a downside—blown stretch film is very noisy to unroll! When properly applied, the extra stretchiness of blown films can deliver superior load securing power, though it also makes it challenging to maintain the proper tension on the film. Blown films are the best choice for low-temperature environments like refrigerated or freezer storage rooms and packing areas.
Regular vs. Pre-Stretch Film
Another term you might wonder about in the stretch wrap industry is "pre-stretch." Pre-stretch film, as its name implies, is mechanically stretched to near its maximum tension level before it is wound onto rolls.
Why would you use pre-stretch film? Pre-stretch wrap offers several advantages:
- Since it has already been stretched, you need less stretching energy while wrapping to get a secure wrap. This allows pre-stretch hand wraps to deliver similar load stability to machine stretch wrapping. It also reduces fatigue and improves safety.
- You'll use a lot less—typically about half the amount compared to regular stretch wrap—resulting in cost savings of 25%-40%.
- It provides better stretch consistency, excellent cling and superior load stabilization.
What's the Best Stretch Wrap for Your Application?
Pantero carries a variety of stretch wraps and films, including bundling wrap, hand stretch wrap and machine stretch film. We carry cast and blown stretch film in addition to specialty wraps such as high-performance equivalent stretch wrap, pre-stretch and opaque and colored stretch films.Not sure which stretch wrap is right for you? Contact one of our stretch wrap experts! We'll be glad to help.