Stretch wrapping is one of the most common tools for unitizing products for transport. However, just because a pallet is wrapped and looks good to the naked eye, does not mean it is wrapped well, efficiently or most importantly… SAFELY. When the proper stretch wrapping is negated, problems can arise during shipping. Depending on the severity of the problem, your business may end up with a bruised reputation and potential safety failures.
Below, we will explore the various types of stretch film so that you can make an educated decision on which is best for your particular applications and needs.
Stretch wrap or stretch film is an extremely elastic plastic wrap that is stretched around various products (such as pallets of boxes) for shipping and transportation. The elastic recovery or stretch-ability of the film secures the products and ensures they are tightly bound.
It is often implemented in the unitizing of various products but can also be leveraged for packaging bundles of small objects. Stretch wrap sticks tightly to itself and is used in millions of companies across the globe.
There are many different types of stretch film. What follows is a list of each type investigating each films capabilities, common uses and varied dynamic qualities.
Machine Stretch Films
Machine stretch film was created to be used by a stretch wrap machine. It has the upper hand over hand film in various ways including but not limited to: quicker and greater efficiency in packaging, lower material spend, greater safety and superior load containment. There are several kinds of machine stretch films: cast machine stretch film, blown machine film and pre-stretched films.
Cast Stretch Film – Cast stretch film is made by applying a comprehensive manufacturing operation called cast extrusion. This action mandates the continual thrusting of a thermoplastic substrate into a flat die and onto a cooled roll. The film gauge is resolved by how quickly the casting roll drags the plastic away from the die. This treatment causes cast films to boast superior clarity, allowing for end users to observe the wrapped objects. This film stretches easier due to the molecules being aligned as they’re extruded.
Cast stretch film is exceedingly quiet when being removed from the roll and is fairly simple to stretch. Cast stretch film also provides two sided cling that grants wrapped product the ability to remain firmly wrapped during transportation.
While cast stretch film has multiple fantastic attributes such as a more affordable cost than blown film, it does not hold a candle to blown film in sustaining strength or protection against tearing. Cast stretch film is generally able to stretch with ease, but does not have as robust of a stretch memory as some other films.
Blown Stretch Film – Blown stretch film is created through a function called blown extrusion. This operation involves plastic melt being pushed into a circular slit die which in turn results in a refined tube. Next, air is pushed into the tube, granting the volume of air enclosed to expand the tube to the optimal width. The tube is topped with an air ring which is then blown onto the substrate to chill. This operation of chilling the material provides the blown film with greater strength and more flexibility than other wraps.
As blown film is generally stronger than the majority of other stretch wraps, it also boasts a greater resistance to tearing. This is advantageous when attaining loads that contain pointy edges which are vulnerable to collapsing thinner films. Blown films provide a high degree of memory when stretched. This means that packages remain secured.
Unfortunately, blown film is more expensive and has poorer transparency compared to other films. It also produces what some consider an annoying level of noise when compared to other similar substrates.
Pre-Stretch Film – Pre-stretched film is expanded near its breaking point before it is wrapped onto rolls. This film does not necessitate as much energy as other stretch films to achieve the same wrapping force. Pre-stretched film consumption often uses around 50 percent less than other stretch films, making for potentially extreme cost reductions.
Hay Baling Stretch Film – Hay baling stretch film is a multi-layer specialty stretch wrapping substrate made for wrapping baled rolls of hay. It is used primarily in the agricultural and farming industries. Also known as silage stretch wrap, many types of these wraps feature LDPE (low density polyethylene) formulations with oxygen barriers to keep your hay bales dry.
Non-Machine Stretch Films
Hand Stretch Film – Hand stretch film is made exclusively to be wrapped by human labor manually. It is also known as hand film, hand stretch wrap, hand wrap or manual pallet wrap. It is commonly used by companies who wrap small volumes of products. Generally speaking, that would be companies who wrap less than 50 pallets per day.
Capabilities of manual stretch film must be continually checked against the various potential improvements that comes with switching to a stretch wrapping machine. Selecting the proper stretch application for your packaging line will make for higher efficiencies and a more cost effective production.
Color Stretch Film – Color stretch films were created to serve a very specialized niche area of packaging needs that other stretch film types cannot properly service. Color stretch film is perfect for warehouse color coding, international transportation or dating inventory. Color stretch wrap is designed to be resistant to puncture.
UVI Stretch Film – Ultra violet film is stretch film with special light discouraging additives that defend it from photographic degeneration in applications where wrapped products are kept outside and are exposed to the elements.
VCI Stretch Film – VCI or Vapor Corrosion Inhibitor stretch film is made specifically for wrapping metal components so they don’t rust. This formulation prevents the oxidation of metals and is commonly used to package tools, metal pipes and other metal products or materials.
Reinforced Stretch Film – Reinforced stretch films are thick films with especially strong formulations which are used to package and protect extremely heavy loads for transportation and shipping. For example, this type of film is commonly used for the palletizing and unitizing of bricks and cinder blocks.
Vented Stretch Film – Vented stretch film is commonly utilized in applications where air flow and oxygen needs to be available to the products being packaged, such as wrapping pallets of wood, hot bakery items, etc.
NO Cling Stretch Film – No cling stretch film is used for packaging products such as carpeting so that the products being packaged can slide on and over each other without getting caught and tearing. There is also a variant of no cling stretch film that has only one side that clings called one-sided cling stretch film.
Specialty Stretch Films– In some cases, specialized types of wrapping projects require the implementation of performance films with multiple layers which have very high stretch capabilities. In addition, gauge reductions can be used resulting in uncommon thicknesses of stretch films for similar applications.
Choosing the Right Film
After familiarizing yourself with the different types of stretch film listed above, you will be able to start formulating your ideas on which is the best fit for your company and the products you are packaging with the packaging machinery or labor force that you have.
Depending on your budget, packaging line and machinery or lack thereof, you may still not be sure which stretch film is right for you. It would be well advised for you to consider reaching out to at least three vendors and asking for recommendations on a film that would best suit your unique needs.
Getting a professional analysis of your packaging line, machinery, labor force and current materials is also a good idea. With the information provided by said analysis, you will be able to choose the best stretch wrapping solution for your business.
Finally, a quality preventative maintenance program will ensure that you are always running the best choice of stretch wrap for your particular applications. As time moves on, this program will allow for expert advice on making changes as new advancements in stretch wrap develop through technological innovation, product considerations and the types of equipment you are utilizing.
Nathan Dube is the digital marketing specialist at Industrial Packaging. He is responsible for creating videos, writing blog posts and generating other pieces of content and multimedia for the company. View the latest podcast here: https://www.youtube.com/watch?v=rNTGmym7xlU.