The Basics of Corrugated

Posted by Ken Wheeler on Tue, Jun 25, 2013 @ 8:15 PM

Corrugated offers the most flexible and innovative packaging solutions available. It has a long and proven history, being used as a reliable packaging material since the 1870s. It’s never been replaced in standard use in all that time because of its demonstrated superiority. Why has corrugated maintained its popularity? 

Corrugated offers the most flexible and innovative packaging solutions available.

Corrugated offers the most flexible and innovative packaging solutions available.

Corrugated material used in packaging is one of the most inexpensive substrates available. Fundamentally, corrugated fiberboard is made of nothing but air, yet surprisingly strong. The fluting of the material, much like arches in a cathedral, allows the material to be flexible and still quite strong.

What makes up corrugated board?

Corrugated can be disguised under a number of different names, sometimes referred to as fiberboard or combined board or even cardboard. Corrugated has two main components: the liner and the medium. Both are made of a special kind of heavy paper called containerboard. The smooth, flat paper that sandwiches the interior fluting is the linerboard. The fluted paper (or medium as it is sometimes referred) is joined to the flat linerboard with adhesive to form the corrugated fiberboard.

Two design factors impact the weight, strength, qualities and characteristics of corrugated fiberboard – fluting and wall construction. Corrugated cardboard walls are manufactured in single, double and even triple-wall thickness. So, the more layers in the cardboard wall, the greater the strength.

Corrugated offers different wall construction

Flutes in the wall construction help to determine its usage. The larger the flute, the stronger the box.  To fulfill various loads of content, corrugated fiberboard is constructed with different kinds and arrangements of flutes. By experimenting with flute profiles, designers can vary compression strength, cushioning strength and thickness.

1) Single-Wall Corrugated Construction
Single-wall consists of one flute sandwiched between two sheets of linerboard. Single-wall corrugated boxes have a wide range of material strength, which is measured in terms of the ECT (Edge Crush Test). The ECT identifies the ability of the assembled box to withstand weight before bursting.

Single-Wall Corrugated Construction

2) Double-Wall Corrugated Construction
The double-wall consists of three sheets of linerboard sandwiching two flutes. The additional fluting makes this construction that much stronger and more resistant to crushing than single-wall cardboard. Heavier and less flexible than single-wall corrugated material, double-wall corrugated cardboard is designed to accommodate heavier content for shipping and storage.
Double-Wall Construction

3) Triple-Wall Corrugated Construction
Three corrugated mediums and four linerboards make up this extra resilient construction. This 7-ply construction is used where large container sizes are involved, such as pallet packs and skirts. Triple-wall corrugated boxes can hold significantly more weight, ranging from 240 to 300 lbs.
Triple-Wall Corrugated

What is fluting?
Without fluting, there would be little to no strength to your package. The types of fluting vary depending upon how many flutes are included per square foot, and how thick the fluting is. Fluting comes in five standard types.

  1. A-Flute: the original flute first invented, its lightweight qualities are often use for wrap, cushioning or stacking.
  2. B-Flute: although it appears thinner than other types, is yet stronger, and is most often use for die-cut boxes, canned goods and displays.
  3. C-Flute: measuring somewhere in the middle, between A and B flutes. C-flute is the most common type of corrugated container material used, typically found in regular slotted shipping cartons.
  4. E-Flute: is a quarter the thickness of C-flute and is the favorite for cosmetics boxes, glass and ceramic containers and pizza boxes.
  5. F-Flute: the lightest in thickness – half the thickness of E-flute. This is a popular “green” solution as it can reduce the total amount of paper fiber in packaging for a more sustainable solution.
Sources: Norampac-Lithotech, Fiber Box Association


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