If you want to run shrink film on your packaging line, you need to understand a wide array of technical terms. From gloss and haze to tensile and elongation, there is a host of technical data that requires understanding.
With decades of experience with shrink film, we here at Industrial Packaging know the material inside and out. In today's article, we will explore the various terms used when interpreting technical data on shrink film.
With the information in this post, you will be able to run shrink film on your packaging line with ease and know how to properly optimize your machinery and materials.
Common Terminology For Interpreting Technical Data On Shrink Film
Haze
It is the actual measurement of the cloudiness of the film. It is typically communicated in a percentage format. The lower the percentage, the clearer the film. If you want your products to be clearly visible on store shelves, you will want a low haze film.
Gloss
Gloss is the measurement of reflected light given off from the surface of the film, given from a certain angle of degree. The higher the number, the glossier the film is.
When interpreting gloss, make sure to keep in mind the angle it is being measured from. The most common is 45 degrees but this measurement can be skewed by using a different angle.
If you want to catch the eyes of consumers, using a high gloss film may help your products to stand out on the shelf.
COF
The coefficient of friction, or COF, is an indicator of the ability of the film to slide against itself or another surface. The higher the COF, the less likely it will be to slip or move.
This item is important if you’re running high-speed shrink packaging equipment. You’ll want to make sure the film flows over inverting heads and forming plows easily.
There are even some applications such as laundry providers that need less slippery film so their bundles of tablecloths don’t end up on the floor during movement within the plant.
Shrinkage MD/TD
Shrinkage (also known as unrestricted shrink), is a percentage of the amount of shrink measured in both the machine direction (MD) as well as the cross direction (TD). The TD direction is 90 degrees to the MD of the film. This is measured as a percentage value.
Tear Resistance MD/TD*
Tear resistance is measured in both the machine directions as well as the transverse direction; tear-resistance represents the ability of the film to resist tearing. Typically, more oriented (high-clarity) films have a higher resistance to tear. As you increase in gauge or thickness, your tear resistance increases. High-clarity films are commonly used to package high-value consumer goods.
Ultimate Tensile MD/TD*
Tensile is measured in both directions as well and is measured as PSI or pounds per square inch. This is the force that the film can withstand from external forces such as poking or tearing.
*Ultimate tensile and tear resistance are especially important if your product has sharp corners or an odd shape that when shrunk drastically pulls on the film.
Elongation MD/TD
Also measured in each direction, elongation is the percentage a film will distort or stretch before breaking. The higher percentage, the more the film will resist tearing or breaking.
MVTR
MVTR or moisture vapor transmission rate is the rate that moisture will pass through the film. Usually measured as grams per 100 square inches over 24 hours. The lower the number, the more resistant it is to moisture transmission. You see lower MVTR rates in films used in packaging applications such as modified atmosphere packaging.
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OTR
OTR or Oxygen transmission rate is a measurement of the permeability of oxygen through film. This is measured by a CC per 100 square inches over 24 hours. The lower the number, the less chance oxygen gets in. You would want a film with a higher number for packaging things that require the presence of oxygen, for example, beef.
Modulus
Modulus is the measurement of the film's stiffness. It is typically measured in both directions, and the lower the numbers are, the softer the film is. Stiff films are commonly used to package CDs and DVDs where softer films are used for applications such as food packaging.
How To Use This Information
Each of the items above can be useful when sourcing shrink film for your packaging line and products. Depending on what you are packaging, you will need to feel comfortable with each of the items above at some levels. Using the wrong type of shrink film for your products results in excessive waste, tearing, improper shrinkage, and other common shrink wrap problems.
By using the information above, you will have a set of tools to better understand the unique characteristics of shrink film and their various gauges. When finding the correct brand, type, gauge, and width of shrink film for your needs, it is essential to do research ahead of time.
To take all of these data points to find the unique formula that helps identify the correct shrink film for your packaging needs, we recommend reaching out to a local packaging expert. If possible, have them come to your facility to physically inspect your packaging line, machinery, and current materials.
This will allow them to identify the appropriate shrink film for your products and packaging line. It would be a good idea to speak with 3-4 different vendors and compare the information and recommendations from each company representative.
Once you have had the opportunity to review the information from each potential vendor, you can then make an educated decision on which vendor has the right solution for your shrink film needs.
If you are unsure of where to start, feel free to contact one of our packaging experts. They will be able to assist and advise on which type of film is right for your needs. Additionally, they will be able to help you choose the right vendor for your applications, even if it is not us.
