Using a shrink tight sheeting to create encapsulation and containment around a scaffolding structure is a demanding application that requires a shrink wrap film that has been engineered / designed for purpose. The quality of a scaffold shrink wrap film is determined by the chemical ingredients used and the manufacturing process.
Contact us to discuss your requirements of Shrink Wrap Film Rolls. Our experienced sales team can help you identify the options that best suit your needs.
Much scaffold shrink wrap available today is simply general plastic sheeting that is being branded and sold as ‘scaffold wrap’. However, those selling it simply don’t understand the problems that poor quality can cause for the scaffolders and contractors at the ‘sharp end’. When scaffold sheeting blows off or doesn’t perform properly somebody has to go back and fix it, and that is usually not the person who sold you the shrink wrap!
Buying guide:
What is scaffold shrink wrap made from?
To make shrink film for scaffolding the resin must be a100% fractional melt virgin resin that is not reprocessed / recycled material, with a primary mixture of low density polyethylene (LDPE) and a secondary mixture of linear-low density polyethylene (LLDPE).
The following additives are used to give scaffold shrink wrap the performance characteristics we need.
There are many flame retardant standards in different countries. In the United Kingdom we use the European EN13501 standard and the LPS1207/1215 scheme.
A light stabilizer (ultra-violet inhibitor/UVI) of the hindered amine gives the shrink film a minimum service life of 1 year. You should be aware that films that if a flame retardant shrink wrap film claims to have a UV stability beyond this it is unlikely to also have enough flame retardancy added as these two additives ‘compete’ with each other.
EVA (ethyl-vinyl-acetate) additive gives the shrink film flexibility, greater puncture resistance, mechanical strength and deters splitting and brittleness in high winds and extreme cold weather.
Anti block agent (slip) prevents the film surfaces from sticking together during the manufacturing process and allows for easy unroll/unfold from the roll by the user. Excess or low quality anti-block material will cause the film surface to feel oily and prevent tape from sticking to the surface or film-to-film-fusion.
Colour additives are used to give the shrink film a white tint that should provide an opacity of at least 65%
The shrink wrap extrusion process starts with the blending of resins and additives. They are melted and blown through a die. After exiting the die the shrink film goes through the air cooling ring and travels up to the guide rolls, where the film bubble is collapsed and flattened and then to the winder where it is rolled on to cores.
The manufacturing process is vital to the following shrink wrap characteristics;
Shrinkage
It may seem obvious, but an important factor in how well a shrink wrap sheeting will encapsulate a scaffolding is how well it shrinks. If a shrink wrap sheet shrinks well, it will fit tightly and it will not flap or ‘chafe’ in high winds. It will be strong.
If you look at the specification sheet of a shrink wrap film you should see that the shrinkage, sometimes known as the ‘shrink ratio’, is described in two ways; Machine Direction (MD) and Transverse Direction (TD). A shrink wrap film should have balanced shrinkage, which means that the shrinkage in both the MD and TD should be similar. However, while most shrink-wrap films have a good shrink ratio % in the Machine Direction (MD) very few have good shrinkage in the Transverse Direction (TD). As well as making the installation process difficult for the shrink wrap installer / end user, a poor shrink ratio may also cause the shrink wrap film to loosen or become slack in the first few days after installation.
So what affects the shrink ratio? It is mostly due to the size of the die from which the shrink wrap film is extruded. At Rhino we use a very small die (700mm) from which the melted plastic polymers are blown into a large bubble of shrink film that has a circumference of 7 metres. This difference between the size of the die and size of bubble, (sometimes called the ‘blow up ratio’), is critical in achieving a powerful shrinkage because when the film is heat shrunk by the end user, around a scaffolding for example, the shrink wrap has a ‘memory’ and will try and return to it’s original size at the point of extrusion.
However, to speed up the manufacturing process most shrink wrap manufacturers use a die that is much larger than we do to manufacture their shrink wrap film. (A larger die has a higher production rate / hour). Typically, a die will be 1800mm to 2000mm wide. This larger die, although making a machine more profitable for the manufacturer, will produce a shrink wrap film with a much poorer shrink ratio, particularly in the transverse direction (TD). So, although our film is a little bit slower to manufacture, by using a smaller die we ensure that our customers get a shrink wrap film that has a shrinkage of 45% in the transverse direction (compared with a typical figure of 10-15% for competitor films). The end result of this is that Rhino shrink wrap is much easier for our customers to install properly, even in tough weather conditions, and once fixed in place is much more resistant to high winds.
Layers
Looking at the specification sheet should also tell you whether the shrink wrap film you are using is a mono (1 layer) film or a multi layer film. In a similar way to ‘die size’, explained above, it is generally more convenient for manufacturers (but not the end user) to supply a multi layered film as it is faster to manufacture and multi layered machines can produce a wide variety of products. However, it can enable unscrupulous manufacturers to ‘hide’ poor quality but cheaper regenerated plastic material within layers.
A mono layer film is slower to manufacture but it means that any additives, such as flame retardancy, are contained throughout the whole film, and not just the outside layers, and it means we can only use premium resins to manufacture our film.
Thickness
Take a micrometer and measure the thickness of the film in different places. The thickness of lower quality films can vary by as much as 50-75 microns and the result is many points of failure (holes) during the heat shrink process.
Dart Drop
This is a very important measure of the basic mechanical strength of the film, which for scaffold shrink wrapping means the wind loading that the shrink wrap will bear. It is a standard test procedure outlined in ISO7765-1/2. Compare between alternative films and try and buy a shrink wrap film with the best performance in this area.
Seal Range
The seal range of Rhino shrink wrap film is in the range of 95 to 125 Degrees Celsius. This is an important value because the lower temperature a film requires to seal, the easier it will be to heat weld by the end user. Again, the reason why some shrink wrap films are difficult to heat weld properly is that they have a much higher seal range and this is because many shrink wrap manufacturers add HDPE to their LDPE films, to speed up the production process and make each machine more profitable. However, an film with HDPE added will have a higher weld temperature and so be more difficult for the end user to weld, especially when weather conditions are challenging. It should not be necessary to apply additional strengthening by applying shrink wrap tape to a welded joint between two pieces of shrink wrap film.
Tensile Strength (Yield)
Another test that relates to strength, but with a focus on elasticity - i.e. the ability of the film to return to it’s original form when hit by a force such as the wind. You may notice that scaffold wrapping films with poor elasticity may sag after time, even if they at first seemed ‘drum tight’ when initially installed. This is due to poor tensile strength.
Always try and purchase from an ISO accredited supplier, as they will have the necessary quality controls in place to ensure consistency between batches. Always ask your supplier for a specification sheet / data sheet and look closely at the shrink ratio, dart drop and seal range.
Most shrink wrap plastic film is made in a way that is most convenient for the manufacturer, even if makes life more difficult for the end user. We think it makes more sense to start with the end user and work backwards to make sure the whole manufacturing process is designed to create a film with the desired performance.
It's important to identify some specifics about your product to be packaged before diving into the details of the films available to you. Without question, a packaging supplier is key to selecting the appropriate film for your needs. Their industry experience and ability to understand your needs gives them the expertise to ascertain which types of films will and won’t work for your product.
Some of the packaging considerations you’ll need to be aware of include:
What type of product you are packaging
The product’s weight, shape, and dimensions
Your objectives for color and labeling
If you are looking for more details, kindly visit Food PETG film.
Whether the film can be printed to meet your needs
How the product will be packaged into the flexible film (manually or via machine, and what type of machine
The product’s journey from creation to shipment to the shelf and beyond
Whether it will be handled often and/or subject to rough handling
The types of climates/environments it will experience
Whether it requires specific film additives to keep it fresh (e.g., oxygen or moisture barrier)
Requirements for anti-tampering and security of the finished good
With so many types of flexible packaging film available, you are sure to find the right packaging for your product. Whether you need an option with a high melting point, one that emphasizes durability, or one that prioritizes recyclability and sustainability, there is a shrink film product available to suit your needs. With all of the opportunities for a custom finish to any product, it’s always important to do your research and consider your specific needs to determine the best options.
Also, you’ll need to do some homework regarding equipment. If you have an automatic shrink wrapper or are planning to purchase one in the future, it’s important to keep an eye on your bag length and running speeds. Sometimes operators adjust the bag length from the original specs to make running the line easier. This is particularly more noticeable on older pneumatic shrink wrap equipment. Running your film at just 1" larger than necessary can equate to 2,000 extra feet of film used per day. That’s approximately 118 wasted rolls of film.
Be sure to think about how capable your internal maintenance technicians are. Adding a shrink film wrapper to your packaging line will require technical support on a regular and as-needed basis. Assess your internal maintenance team’s comfort level with working on the new machine(s), and make sure you have a backup technician for when service is needed and your internal team can’t handle the repair.
Before purchasing and storing shrink film, make sure you know its storage requirements. You don’t want to try to work with climate-compromised packaging. Your supplier should have this information available if you’re unsure what your material requires. Overall, shrink packaging is best stored in temperatures between 30 and 77 degrees Fahrenheit. Naturally, summer and winter are the seasons that require you to be most attentive to your storage environment.
Your facility will likely be subject to high heat in the summer, if not during springtime. If shrink sleeves are kept in temperatures exceeding 100 degrees, they may prematurely shrink and compromise their ability to protect your goods. During these hot months, keep your shrink materials stored in the coolest areas of your facility without subjecting them to refrigeration.
They should be kept cool, but not too cold. The coolest spots in your warehouse are typically close to the floors – on the lowest part of your pallet racks – and away from windows or places that are subject to a lot of sunlight. You’ll also want to keep your shrink films away from high-traffic doors because the temperatures in these areas tend to fluctuate greatly.
Additionally, try to schedule your shrink film deliveries early in the day. That way, the materials won’t sit in the back of a hot trailer when traveling from warehouse to warehouse. Not only will you avoid the harshest hours of the sun, but you’ll also give yourself more time to store them before the temperature reaches its peak.
:
As mentioned, packaging films tend to become especially brittle in cold temperatures, which greatly reduces their stretching and shrinking properties. While the PVC may crack, it can even shatter like glass if left in extremely cold conditions for too long.
As in the summer, store your rolls away from doors to avoid temperature fluctuations. You also want to ensure rain or snow won’t create unwanted moisture in the rolls. If you’ve been using PVC shrink film to package frozen foods or other products that spend time in a freezer truck or refrigerator, consider switching to a polyolefin film. This is a more durable, food-safe, and recyclable material that will keep your package intact during transit and packaging.
When you take shrink film out of storage, you may not know how to tell if it’s been compromised. One key sign is sticky rolls. If PVC rolls stick together, they were likely exposed to too much heat. Don't risk downtime on the packaging line by trying to use them anyway. Skip over the rolls that are stuck together. Bagging and sagging are also signs of overheated film. The rolls may begin to sag on the edges or show bagging within their layers. Using these rolls can interfere with the tracking on your machines, so avoid using these compromised rolls as well.
Remember, even the highest-quality shrink film and packaging materials are apt to deteriorate when subject to these environmental factors. No matter what quality film rolls you’re purchasing, take the time to assess how you’ll store them to ensure they protect and present your product exactly as you’ve planned.
Finally, keep your target audience at the forefront of your packaging design. The type of material you choose is a part of your brand, so any disconnect between that and your brand’s message will confuse consumers and make them lose trust. To appeal to your customers, you have to research and understand them enough before you make these key marketing and branding decisions. Market research is a great way to learn what your target audience values and decide how to pair those details with your budget, transportation, and sustainability needs and goals. Always listen to your key demographic and cater to their needs specifically.
For a quick look at some additional considerations regarding your use of shrink wrap film, check out this free shrink film cheat sheet.
Are you interested in learning more about Beverage Shrink Film? Contact us today to secure an expert consultation!