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What is Corrugated Fiberboard?

Updated: May 21, 2022

Wisconsin Green uses corrugated fiberboard which is a material consisting of a flutedcorrugated sheet and one or two flat linerboards. Made on "flute lamination machines" or "corrugators," it is primarily used for making cardboard boxes. The corrugated medium sheet and the linerboard(s) are made of kraft containerboard, a paperboard material usually over 0.01 inches (0.25 mm) thick. Corrugated fiberboard is sometimes referred to as 'corrugated cardboard', although cardboard might be any heavy paper pulp-based board.

Now let’s take a quick brief look at the the History of Corrugated Fiberboard.

Corrugated (also called pleated) paper was

Patented in England in 1856, corrugated (also called pleated) paper was used as a liner for tall hats. It wasn’t until December 20, 1871 that corrugated boxboard was patented and used as a shipping material. The patent was issued to Albert Jones of New York City for single-sided (single-face) corrugated board. Jones used the corrugated board for wrapping bottles and glass lantern chimneys. The first machine for producing large quantities of corrugated board was built in 1874 by G. Smyth, and in the same year Oliver Long improved upon Jones' design by inventing corrugated board with liner sheets on both sides, thereby inventing corrugated board as it came to be known in modern times.

In 1890 Scottish-born Robert Gair invented the pre-cut paperboard box which consisted of flat pieces manufactured in bulk that folded into boxes. Gair's invention resulted from an accident. He was a Brooklyn printer and paper-bag maker during the 1870s. While he was printing seed bags, a metal ruler used to crease bags shifted in position and cut them. Gair discovered that by cutting and creasing in one operation he could make prefabricated paperboard boxes. Applying this idea to corrugated boxboard was a straightforward development when the material became available in the early 20th century.

First used for packaging glass and pottery containers, it wasn’t until the mid-1950s that the case enabled fruit and produce to be shipped from farm to retailer without bruising. This was an important development in agriculture as it substantially improved the return to producers and opened new export markets.

Corrugated board is manufactured on large high-precision machinery lines called corrugators, usually running at about 500 feet per minute (150 m/min) or more. These machines, over time, have become very complex with the objective of avoiding some common problems in corrugated board production, such as warp and wash boarding.

The key raw material in corrugating is paper, different grades for each layer making up the corrugated box. Due to supply chain and scale considerations, paper is produced in separate plants called paper mills. Most corrugating plants keep an inventory of paper reels.

In the classical corrugator, the paper is softened with high-pressure steam. After the board is formed it is dried in the so-called dry end. Here the newly formed corrugated board is heated from the bottom by hot plates. On the top, various pressures are applied by a load system on the belt.

The corrugated medium is often 0.026 pounds per square foot (130 grams per square meter) basis weight in the US; in the UK, a 90 grams per square meter (0.018 lb./sq ft) fluting paper is common. At the single facer, it is heated, moistened, and formed into a fluted pattern on geared wheels. This is joined to a flat linerboard with a starch-based adhesive to form single face board. At the double-backer, a second flat linerboard is adhered to the other side of the fluted medium to form single wall corrugated board. Linerboards are test liners (recycled paper) or kraft paperboard (of various grades). The liner may be bleached white, mottled white, colored, or preprinted.

Common flute sizes are "A", "B", "C", "E" and "F" or microflute. The letter designation relates to the order that the flutes were invented, not the relative sizes. Flute size refers to the number of flutes per linear foot, although the actual flute dimensions for different corrugator manufacturers may vary slightly. Measuring the number of flutes per linear foot is a more reliable method of identifying flute size than measuring board thickness, which can vary due to manufacturing conditions. The most common flute size in corrugated boxes is "C" flute.

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