All About The Ply Value In Corrugated Carton Boxes

Packing and the quality of your cartons is the central concern for product quality. If your goods are not well packed, then it can cost problems throughout the supply chain.

Knowing the different ply values in corrugated cartons is an essential part of understanding packing carton quality. Corrugated cartons are constructed with kraft or test paper made into the cartons using flute construction. The most common corrugated cartons are 3-ply, 5-ply, and 7-ply corrugated cartons.

All About Corrugated Paper Used in Cartons

Corrugated cardboard is made up of three different components. The three components are shown below:

Photograph of Cardboard
Flute and Linear Paper on Corrugated Cardboard.

For corrugated cardboard, you have a fluted material in the center which is placed between two layers of paper. It is the center corrugated piece that makes this a “corrugated cardboard box.”

Like most things, the quality of the carton depends on many factors. One of the key factors for the quality of the carton is the type of paper used.

The type of paper used depends on many things, and one is simply what kind and quality of paper are available locally where the cardboard is being manufactured. Another is if the cardboard supplier has all the necessary technological expertise.

Two common types of paper are used in corrugated cartons, i.e., kraft and test paper; here is what each of these means:

  • Kraft Paper – Kraft paper is usually manufactured from softwood trees. This means that the paper is considered to be “virgin” paper. Kraft paper is the strongest type of paper and also the easiest type to print on. As a result, most corrugated cardboard suppliers will use Kraft paper on the outside side of the corrugated carton. In addition, most manufacturers need to print a shipping mark on the outside of the carton.
  • Test Paper – Test paper is recycled paper. It is actually a double-layered paper. It is not as strong as kraft paper or as easy to print on, so it is commonly used for the inner liner of a carton.

Like most kinds of paper, the quality of the paper can vary greatly according to the technology and how the paper manufacturer can make the paper. The quality of the paper also depends on the actual paperweight.

When we talk about weights for the paper, we normally talk about GSM. GSM is an abbreviation of grams per square meter. So this means that if you took a square meter of paper and weigh it, this would be the weight or grams per square meter of that paper.

Another important part of any corrugated cardboard is the flute. This is because the sizes of flute can vary as much as the cardboard. The size of the flute is counted as how many loops there are per linear foot. A double wall carton, for example, would have two rows of flutes

If this is seeming all a bit technical – it actually is. There are so many variables that can distinguish which corrugated carton box is of the quality needed to protect the products.

The Ply Value In Corrugated Carton Boxes Explained

Now that we understand a little bit about the flutes and how a corrugated cardboard box is constructed, we can talk about the difference between what each of the cardboard ply values.

Below are some of the major differences between the different ply values of corrugated cartons that are being used:

Diagram Cardboard Plys
3-ply, 5-Ply and 7- Ply Cardboard Diagram.

3-Ply Corrugated Carton

A 3-ply corrugated carton has 1 flute between 2 line boards. This three-ply corrugated carton is normally used as an inner carton or a carton for any lightweight products. In other words, it is good for shipping and storing products that are not heavy or using them as an inner carton that will be placed inside of a stronger outer carton.

We will not use a 3-ply carton as the outer carton for most of the products that we produce,
as it is not strong enough. Still, we will only use a 3-ply corrugated carton as an inner carton—a normal 3-ply corrugated carton and handle about 4 to 15 kilos or 8 to 33 pounds.

5-Ply Corrugated Carton

A 5-ply corrugated carton will have 2 sections of fluted paper sandwiched between 3 linear boards. A 5-ply carton and can usually handle pressure and be stacked up for transportation.

This is one of the most common cartons used to export goods. The 5-ply corrugated cartons are economical, plus they are strong and can handle a lot of weight and handling.

A 5 ply carton that is made well can handle a lot of weight and handling.

7-Ply Corrugated Carton

A 7-ply corrugated carton would have 3 layers of flutes between 4 linear boards This carton has one extra row of flutes and linear boards from a 5-ply carton.

A 7-ply cartons should be used to pack items such as very heavy furniture, metal parts, or items which required a very strong carton.               

When considering; which kind of corrugated carton to use for your products or shipment of goods, you should conduct a product drop test. To learn more about how to conduct a drop test on your products you can read our blog What is a Product Packaging Drop-test? by clicking here.

At Mondoro, we understand that the correct packaging is essential to our customers. That is why we always strive to have the best quality carton that we can find. We also regularly conduct product drop tests.

If you are interested to find out more about how Mondoro can help you create, develop and manufacture great home decor and home furniture products – feel free to contact me, Anita. at my email by clicking here or become a part of our community and join our newsletter by clicking here.

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Anita Hummel

Hi, I am Anita Hummel. I am the President of Mondoro. I am passionate about helping you CREATE, DEVELOP, and MANUFACTURE home decor and home furnishing products. I am also an avid blogger with a love of travel and riding my motorcycle around the streets of Hanoi, Vietnam.

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