Because of their long life, strength and durability, corrugated boxes are the preferred container in shipping and storage applications. They are also used to organize materials in the short term, as in offices, homes and mail delivery. The corrugation process strengthens these fiberboard containers while maintaining very low weight.
Because of their affordability, low weight and strength, people come across corrugated boxes in many applications every day. They are used to store and ship many consumer products, and as packaging for products from toothpaste and cereal to computer paper and soap. Oftentimes with consumer products like these, the corrugated containers have a shiny, wax-like finish applied, with company logos, brand names and graphics added to the packaging. Retail clothing store boxes, jewelry boxes, gift boxes, pizza boxes and containers for baked goods and cakes are all made of corrugated paper materials.
Some of the countless industries that rely on corrugated containers every day include auto parts, hardware, tools, food processing, health care, construction, toys, publishing and restaurants, to name just a few.
Corrugated paper materials have been used as packaging for over 150 years. Before that time, paper products were simply too expensive due to the laborious processes by which they were made, most often by hand. With the advent of industrial processing techniques of wood pulp, paper packaging materials became more and more affordable and widely used. This occurred in the mid 19th century during the Industrial Revolution.
In the mid-1850s, a patent was issued in the United Kingdom for the first corrugated paper; this was used to line hats. Over a decade later an American, Albert Jones, received a patent for the first corrugated board. This board, developed in the early 1870s, had just a single face, unlike the ubiquitous three-layer corrugated fiberboard in use today. It was the first such material used for shipping. Building upon Jones’ design, the inventor Oliver Long developed, in 1874, corrugated fiberboard with two flat faces around a central layer of corrugated fiberboard. In the same year G. Smyth invented the very first industrial corrugator machine that could mass-produce these materials.
The type of corrugated shipping boxes used today, and the materials from which they are made, were not fully developed until the late 1800s and early 1900s. Swedish chemist and inventor Carl Dahl used, in 1884, pulverized wood chips to create a strong product known as kraft paper, which was also resistant to tearing. By the early 20th century manufacturers were producing kraft paper on a regular basis. But still, corrugated shipping boxes as we now know them were not developed until a New York printer named Robert Gair, in 1890, accidentally stumbled upon a way to make them. Gair discovered the process when a tool meant to crease paper seed bags malfunctioned and cut the bags instead.
At first corrugated boxes were mainly used to package fragile items such as ceramics, glass products and the like. But in time, more and more products, such as produce from farms, came to be shipped in corrugated fiberboard containers. By the 1990s, in the U.S. alone, manufacturers produced 25 million tons of corrugated fiberboard. Paper, once an expensive and hardly used material, had become widespread because of its affordability, strength and durability.
How They Are Made
Today, corrugated boxes are typically made from kraft paper, a high quality paperboard derived from wood. When an even stronger container is required they can be made from corrugated plastic.
Paper mills and corrugating plants, respectively, produce kraft paper and corrugated boxes, separately. This allows for maximum efficiency. To make kraft paper, mills use recycled paper, sawdust and wood chips, which are bound together to produce heavy-duty paper using an adhesive, pressure and heat.
Pine trees are the raw materials used to manufacture kraft paper and corrugated boxes. Therefore, many large manufacturers own not only paper mills, but also vast tracts of pine forest consisting of hundreds or thousands of acres.
In the mills, pine trunks that have had their branches cut off are stripped of bark and cut into small wood chips, then undergo a chemical process known as the kraft process or sulfate process. At this stage the chips are turned into fibrous pulp by “cooking” in an alkaline solution made primarily of sodium hydroxide. Next the pulp is dehydrated in Fourdrinier machines, turning it into paper. Finally, the paper mills output reels of kraft paper, which are shipped to corrugating plants and stored as inventory.
Manufacturers use huge machines called corrugators, which can be 300 feet long, to corrugate the kraft paper. First, these machines soften the kraft paper in preheating rollers at high pressure and humidity, making it easier to form the flutes or ripples. Then corrugated molds are pressed into the cardboard to form the fluted board. Two glue stations next join this newly corrugated material to the outer flat layers using a corn starch-based adhesive, making a complete piece of corrugated fiberboard. After drying this material over hot, steamy pates, the surface may be sanded smooth and in some cases coated with a waterproof, glossy finish. Finally, the massive corrugator machine divides the continuous fiberboard into box blanks, large sheets ready to be cut into different sizes. Many of the corrugator machines manufacturers use can produce 500 feet per minute of corrugated fiberboard.
Box making machines then produce actual containers or boxes from this corrugated fiberboard, which are sold typically in bulk bundles of 20-50 or more. To save space during shipping the bundled boxes are sold flat rather than assembled into box form.
Types of Boxes and Corrugated Fiberboard
Though technical differences exist between them, people often use the terms corrugated material, cardboard and paperboard interchangeably. People in the packaging and shipping industries tend to avoid using the word cardboard, a generic term that can refer to any heavy material made from paper pulp, because it is imprecise.
Along the same lines, paperboard technically means heavy wood- or paper-based material that is generally thicker than regular sheet paper. Another term, chipboard, is a bit more precise. It refers to recycled paper that has been pressed to a certain thickness; many light items such as cereal and board games are packaged in boxes made from chipboard.
Corrugated fiberboard refers to the three-layered kraft paper most commonly used to produce corrugated boxes. By definition corrugated here means containing pleats or ripples, known in the industry as flutes. Like pleats, these ripples contain air, which makes these boxes more durable and provides a cushion for anything stored or shipped within them.
Both the types of corrugated fiberboard and the types of boxes made can be customized depending on the end use of the container or box. Flute size, materials used to make the box and binding adhesives all vary. With smaller flutes or pleats, there is better structural integrity and more room for marketing text. Larger flute sizes, on the other hand, offer more cushioning for the contents of the box. The number of flutes and their sizes affect variables like board thickness, cushioning strength and compression strength. Within a single container or box flute sizes and spacing can vary as well.
The size, shape, lids, finishes and ways of closing containers all vary too. Box shapes include square, rectangular and cylindrical, though boxes can be custom manufactured to fit virtually any object. Die cutting machines use either a sharp metal blade or laser to cut boxes into unusual shapes. They may have a detachable lid or be made of a single piece of fiberboard with flaps that fold. End users assemble each box by folding the flat board when ready for a specific use. Some containers are held together by tape or other fasteners, while folding boxes require no tape—folded flaps hold the assembled box in place.
Custom-made boxes used for shipping, storage and organization may have dividers, text and images printed on them, be waxed, or come in a variety of finishes. For commercial products such as soap, cereal and toothpaste, manufacturers make corrugated boxes with a glossy, laminated finish printed with brand names, logos and information. Bleaching or mottling the exterior of the corrugated fiberboard produces white cardboard boxes by removing the dark brown pigment. These and natural brown boxes are the most commonly used.
There are many advantages to using corrugated boxes and containers. They: can be recycled; are inexpensive and lightweight; are durable and versatile; are a reliable way to ship goods and protect them in transit; and they provide an ideal surface on which to print text and graphics.
There are, however, downsides to corrugated boxes. These containers cannot be used to ship heavier items, and in some industries where sanitary concerns are paramount, such as medical supplies and hospital food storage, fear of contamination from insect infestation and liquid absorption preclude the use of corrugated fiberboard containers.
Care, Safety and Compliance Standards
Keeping corrugated containers dry is essential to maintain their strength and durability, as moisture undermines these fundamental properties. Also, like wood that is easier to split along the grain, corrugated boxes made of fiberboard are directionally dependent or anisotropic. They will not function properly if handled in a manner inconsistent with their intended anisotropy or directionality.
U.S.-based ASTM International sets the technical standards governing the corrugated packaging industry. These standards assess properties of corrugated fiberboard and the products made from it, such as tear resistance, weight limits and breaking strength, as well as setting industry standard practices for fiberboard and box construction and for closing and sealing shipping and storage boxes safely.
Things to Consider/Choosing the Right Manufacturer
In the United States alone, there are more than 1,000 manufacturers of corrugated boxes and similar containers. It is therefore key to find the right one for your specific needs. Discuss with potential suppliers: whether they have been certified; their compliance with the aforementioned ASTM International standards; manufacturing timelines; how they will ship your boxes to you; the end use for which you need the products; and if they are able to develop the custom solutions you need, such as printing text and graphics on the containers, any unusual shapes or sizes you may need, dividers and custom finishes such as waxed corrugated boxes.
Additional things to consider include whether the packaging will enhance your company’s brand; whether you should measure the container internally (for shipping products to customers) or externally (for in-house uses); container strength (which is based on the grade of kraft paper used to manufacture the container); and the level of product security you require.
Corrugated Box Terms
Box Plants – A factory that produces corrugated and/or cardboard boxes.
Cardboard – Any heavy paper-pulp based board. Cardboard is not necessarily corrugated. To be “corrugated”, board must have fluted paper with air pockets in the middle of its outer layers.
Cardboard Bins – Cardboard containers that are usually trapezoidal or rectangular and do not include a lid.
Cardboard Storage Boxes – Cardboard containers that are used for storage purposes.
Converting Machines – Convert flat corrugated boards into boxes. Machine types may include flexfolder gluers and die cutters.
Corragated Boxes – A misspelling of “corrugated boxes,” containers made of a corrugated material.
Corrugated Cartons – Corrugated containers, many of which are specially designed to fit a specific product.
Corrugated Paperboard – Two sheets of stiff paper joined by a middle sheet of pleated paper.
Corrugated Trays – Often used for display purposes or used with a shrink-wrap covering.
Corrugating Medium – The wavy “fluted” paper inside the corrugated paperboard.
Corrugating Rolls – Gear-like cylinders that shape paper into a series of waves or “flutes”.
Die-cut Machines – These are machines that cut the corrugated board into a pattern that will later be folded into a box shape.
Five Panel Folder Boxes – Shipped flat without any folding joints. The box has five long panels, one of which fully overlaps. The ends also fully overlap.
Flutes – Ridges pressed or folded into a paper. Flutes are very similar to pleats and come in sizes A, B, C, E, F and micro-flute. The most common size flute is size C.
Full Overlap Boxes – Made with the major flaps fully overlapping, increasing the stability of the seal.
Full Telescope Boxes – Have two telescoping sections. The sections may be formed using staples, die-cut locks or adhesive.
Liner – Also known as paperboard, this material has a similar appearance to the brown paper that composes grocery bags.
Partial Telescope Boxes – Have two sections. The top telescopes partially over the bottom.
Single-face Web – A continuous sheet of flat paper with fluted paper glued to it.
Web – A long sheet of paper on a roll, the web is drawn into corrugating rolls to begin forming corrugated paperboard.