Stretch Film 101 - Doverco
By Barry Kaufman
Director of Operations & Teacher at Concordia University
Date: Nov 12 2024
Categories:
Pallet plastic wrap, packaging supplies, industrial films, high performance stretch film, pre-stretched wrap, shipping material, protective packaging, packaging for pallets.
Stretch Film 101
What is stretch film?
Stretch film is an elastic film that is unwrapped from a roll, often stretched (either manually or mechanically), and wrapped around a unit load to maintain load stability and provide product protection during transport and storage. The film acts like a compression bandage around the entire unit load, creating a “hugging” force to keep everything together and stable.1
Benefits of using stretch film
Stretch wrap film is the lowest cost packaging solution for unitizing a pallet. With proper containment, damage is reduced and product is protected throughout its distribution journey2. Stretch film is available in transparent for easy scanning and opaque varieties to conceal products if desired. Packaging pallets in stretch film also makes tampering immediately evident. ‘’Containment force is affected by the amount of pre-stretch and post-stretch applied to the film through different settings on the wrapping machine3.’’
Stretch film is either transparent, for easy scanning, or opaque to conceal products as desired. Packaging pallets in stretch film can also make tampering immediately evident.
Why and when you should use hand stretch film and machine stretch film?
When it comes to choosing the right stretch film for your packaging needs, understanding the difference between hand stretch film and machine stretch film is crucial.
What is Hand Stretch Film?
Hand stretch wrap, as the name suggests, is manually applied to wrap and secure products. It is designed to be highly stretchable and adheres well to itself, making it ideal for bundling items together securely. This type of film shines in smaller operations or situations where wrapping volume doesn’t justify investing in machinery.
The primary advantage of hand stretch film lies in its convenience and accessibility; it requires no machinery, is easy to use, and provides quick packaging solutions. Whether you're dealing with off-site packaging, irregularly shaped items, or small batches, hand stretch film offers a practical solution that doesn't compromise on security.
What is Machine Stretch Film?
On the other hand, machine stretch wrap is specifically crafted for use with automated or semi-automated wrapping machines. This type excels in operations characterized by higher volumes of packaging. Machine stretch film brings a host of benefits:
- It significantly boosts productivity by allowing loads to be wrapped faster and more consistently than manual methods ever could.
- The pre-stretch capabilities of these machines will lead to less overall film usage—translating into increased efficiency, reduced packaging costs, and improved load stability.
What is the difference between cast and blown film?
Cast stretch film is a popular choice for wrapping items because it has many advantages, including superior transparency, strong tear and puncture resistance, a quiet unwind and lower waste (since it is produced in thinner gauges).
Blown stretch wrap has higher durability and better cling performance, especially in lower temperatures. This makes it a better option for wrapping in a refrigerated or freezer environment4.
Stretch Film Glossary:
- Blown Stretch Film- Derived from the blown extrusion process that has higher durability and better cling performance.
- Bottom Wraps-The wraps a stretch wrap machine uses to apply film to the bottom section of the load. Forming a secure bottom wrap will help to ensure load stability.
- Cast Stretch Film- Derived from the cast extrusion process. Less manufacturing costs allow cast stretch film to be the more widely used.
- Cling- Allows the film to stick to itself and not the product. Some have one-sided cling, and others have two-sided cling.
- Co-extrusion- Extruding two or more materials through a single die to enable the two materials to merge.
- Dart Drop- A commonly used test to measure the puncture strength. It's conducted by dropping a semi-circular shaped object onto the film.
- Elastic Recovery-The ability to recover to its original shape after being stretched.
- Elmendorf Tear-Another standard test used to measure tear resistance.
- Extruder- Equipment used to change solid polymers into molten polymers.
- Film Feed-In a stretch wrap machine, it is the speed at which stretch film is supplied to the load.
- Film Force-Refers to the amount of tension applied to the film as the film is applied to the load.
- Film Memory- The ability to return to its pre-stretched form. Enabling the film to maintain a tight load during transportation.
- Film Tail-The start and end pieces of stretch film applied to the load. The first tail tied to the pallet, and the end tucked or tied off.
- Gauge-A measurement used to measure film thickness or caliper. One gauge is equal to .254 microns. Microns are the common form of measurement.
- Gloss- The amount of light reflected from a film’s surface. Cast stretch films tend to have a higher gloss than blown stretch films.
- Haze- Refers to a lack of clarity. Thicker plastic films generally have more haze than thinner films.
Do you want to reduce your packaging costs?
Explore our wide range of stretch films and discover how our high-performance films provide superior load containment, helping you save costs and reduce your plastic usage.
Doverco offers a free packaging analysis, where one of our experts visits your premises to gain a thorough understanding of your working environment and production. This visit is entirely free of charge, with no purchase obligation.
1Bisha, James Victor. (2012), Correlation of the Elastic Properties of Stretch Film on Unit Load Containment, Virginia Tech: https://www.unitload.vt.edu/content/dam/unitload_vt_edu/graduate-research-and-subpages-pictures-and-docs/thesis-and-dissertations-/Bisha%20-%20ETD%20-%20Correlation%20of%20the%20elastic%20properties%20of%20stretch%20film%20on%20unit%20load%20containment.pdf
2Singh, Jay and al. (2014), The Effect of Stretch Wrap Prestretch on Unitized Load Containment, Packaging Technology and Science: https://www.researchgate.net/publication/261702805_The_Effect_of_Stretch_Wrap_Prestretch_on_Unitized_Load_Containment
3Reynolds, Madison and al. (2019), Effect of Time and Temperature on Stretch Wrap, Virginia Tech : https://www.unitload.vt.edu/research/undergraduate-research/recent-undergraduate-research/undergraduate-research-temperature-stretchwrap.html
4(2023), Blown vs cast stretch wrap: What are the differences & benefits? https://www.ipoly.uk.com/news/differences-between-cast-vs-blown-stretch-wrap