This article is an in-depth guide to how cardboard boxes are made.
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A cardboard box is a shipping container made of layers of heavy-duty paper more than 0.01 inch (0.25 mm) thick. The term cardboard is used as a generic descriptor for various types of solid firm papers used to produce boxes. The general term cardboard box includes several types of paper boxes, such as corrugated boxes and chipboard boxes.
The various shapes of cardboard boxes are produced by folding, cutting, and shaping the sheets of heavy duty layered papers.
Chipboard boxes are part of the recycling industry and are made of recycled cardboard, paper, paper scraps, and sawdust that have been shredded and compressed into firm panels. It has a similar construction to that of cardboard since it consists of materials that have been compressed and glued to form solid firm sheets.
Cardboard boxes are designed and constructed to serve as protection for materials and products. They are lightweight with firm sides that can cushion impacts and contain products such as clothing and toys.
Sheets of cardboard are used as dividers for larger more durable boxes as well as padding.
A major factor in the wide use of cardboard boxes is their ability to be recycled, making them less costly than other forms of containers. The layers of paper used to produce cardboard boxes can be shredded, chemically treated, and formed into rolls to produce recycled paper or chipboard.
Ninety percent of all materials purchased are shipped using cardboard boxes, with over 88 percent being made from recycled raw materials. Making cardboard boxes from scratch requires a great deal of energy and several trees. Cardboard boxes made from recycled raw materials require drastically less energy and eliminate them from being added to a landfill where they can release harmful toxins.
Cardboard boxes come in all sorts of shapes, sizes, configurations, and forms designed to fit the specific needs of a product. The standard cardboard box is made of paper from recycled boxes or the pulp of trees. The final paperboard consists of layers of pulp that have been treated, shaped, and pressed together.
The manufacture of cardboard boxes begins with heavy-duty papers created from tree pulp. The fibers from trees are put through a variety of treatments to produce the stable raw materials for making boxes.
Pulping is the process that is used to manufacture the paper for paperboard. It is a method for dispersing raw materials into single fibers referred to as paper pulp. The purpose of pulping is to dissolve the lignin of fiber materials without the loss of fibers. The method used to complete the pulping process varies between manufacturers and includes chemical, mechanical, and bio forms. The critical element in all pulping processes is 26.4 gallons (100 L) of water, which is necessary to produce one kilogram of paper.
Mechanical pulping is an aggressive physical method that separates the fibers and does not include any chemicals. Instead, wood chips, ground by stones, are bathed in water to form a pulp. The advantages of mechanical pulping include high yield and no pollution. The downside of the process is the low strength of the pulp that is produced.
Chemical pulping is a chemical and mechanical process in which wood chips are cooked and ground to produce cellulose fibers. It is a better separation process that is used to produce high-quality paper.
The presence of lignin in virgin pulp gives it a very dark brown natural color. In order for it to be used for paperboard, the pulp must be bleached to purify it and change its color. Whether pulp is being used or recycled cardboard, the bleaching process is necessary to purify the raw materials. In the case of recycled cardboard, bleaching removes any chemicals from the cardboard.
Different bleaching methods are used depending on the color of the pulp, types of chemicals used, and the types of treatment. The three categories of bleaching are delignification, oxidation, and reduction, each of which is a chemical process.
The pulp is passed through a series of blades designed to flatten the fibers and create the fibrillated ends to assist in the bonding process to make the paper stronger. Fillers are added to increase the density of the pulp and make it opaque. At this stage, the pulp is ready to be processed by the paper machine.
The paper machine consists of different machines that dry the pulp by forcing it through rotating wires and belts to remove the water. Pressure and temperature extract any remaining moisture before being placed on giant paper rolls.
Paperboard is formed in layers of pulp that are sprayed in water onto a mesh screen to form a mat. Spraying the pulp slurry onto a mat builds up the fibers of the pulp to increase and solidify the strength of the paperboard. Each type or grade of paperboard is carefully mixed to match the requirements to meet its grade standards.
Once the mat is formed, the accumulated water has to be removed. Initially, the mat passes over a foundation screen where 20% of the water drips out by gravity. For further processing, the mat moves through sponge rollers that press and squeeze the water out of the mat. After being squeezed, the mat has sufficient strength to be stretched and heated as the final step in the drying process and water removal. The moisture content is at 5% after drying.
The fully formed paperboard is cut to various widths and rolled into huge rolls to be sent to box manufacturing. The different widths allow manufacturers to produce different size boxes in shapes, configurations, and forms to meet customer specifications.
The dried and finished paperboard may be sent on for further processing, where it will be coated with a polymer, which consists of melted pellets that are extruded onto the surface of the paperboard in an extremely thin layer. In preparation for the coating process, a starch solution is added to bind the fibers to the surface and add strength to the board.
Before applying the coating, the paperboard is pressed between steel rolls to even its surface, increase its strength, and equalize the board’s thickness and density. The coating is applied on one or both sides of the board and smoothed over its surface. It is then dried and reeled onto a steel core, after which the long reel is cut into different widths. To meet customer specifications, the paperboard may be wrapped and bound as rolls or trimmed into sheets of varying sizes.
The finished paperboard has a smooth, waxy texture similar to the consistency found on a milk or juice carton.
The finished paperboard is delivered to box manufacturers, which is formed into several types of boxes depending on the customer's needs. During the processing of the paperboard, handles, flaps, and slits are added, and the paperboard is scored such that it can be folded into different box shapes.
The processes for converting paperboard into lightweight cardboard boxes varies depending on the manufacturer.
Huge rolls of paper are delivered to the box-making factory. The width of the rolls comes in various to fit the boxes to be made.
Kraft, German for strength, paper is made from softwood trees with long fibers, such as pine, spruce, or fir trees. The tension of the long fibers makes Kraft paper tear and burst-resistant. Its brown or yellowish color differs depending on the types of trees from which it has been crafted. Spruce, pine, and silver birch trees produce a very dark brown kraft paper, while other trees produce yellowish Kraft paper. In addition to the different types of trees, the quality and color of Kraft paper vary depending on where in the world the trees are located.
Once the first liner is glued in place, Kraft paper is glued to the other side of the flutes. This configuration is the simplest form of corrugated board and is referred to as a single wall corrugated board, which can be seen in the image on the left below. Other forms can have two flutes and two liners with Kraft paper, pictured on the right below. Additionally, the width of the curves varies depending on the design of the box.
For many years, kraft paper has been used to produce corrugated boxes. Since it is such a durable and tear resistant paper, it has also found use in the production of rigid and sturdy cardboard boxes. One of the reasons for using kraft paper is its textured and porous surface, which makes it ideal for printing and producing display boxes.
Unlike the other papers used to produce cardboard boxes, kraft paper has a rustic and raw appearance. Its versatility offers designers a wide range of possibilities for packaging solutions and cardboard box engineering.
Chipboard is a form of thick fiber paper made from recycled paper, wood waste, paper shreds, and sawdust that is turned into a slurry, much like paperboard, using urea formaldehyde. The slurry mixture is placed under pressure and heated to form panels. Chipboard is a very popular form of shipping material used to produce boxes, padding, and other forms of packaging.
Although the terms chipboard and cardboard are used interchangeably, they are two unique, and distinct products. Unlike cardboard or corrugated sheets made from layers of paper, chipboard is completely recycled paper that has been compressed into panels. It is an exceptionally versatile and sturdy paper stock capable of withstanding the same stresses as cardboard and corrugated sheets.
Chipboard comes in several varieties of densities or thicknesses and is a form of solid, sturdy paper. It is an ideal replacement for corrugated cardboard and is used to make cartons, boxes, and sheets of different sizes with different strengths.
The process of manufacturing chipboard involves compressing minute pieces of scrap paper, cardboard, and sawdust with glue to form firm, strong, and durable panels. The scraps used to manufacture chipboard are waste materials discarded from fabrication processes or collected from recycling bins.
Most chipboards are brown and are referred to as Kraft chipboards, with varieties made from newspapers having a grayish tinge. In some processes, it is clay coated, which gives it a thin white appearance.
The raw materials used to manufacture chipboard are left over waste from other manufacturing processes or scrap cardboard, paper, and packaging material from recycling. In order to be suitable for the manufacture of chipboard, the waste materials have to be transformed into a granular form.
In order to create the correct texture, the raw materials are put through a shredder chipper that grinds and pulverizes the material into a fine powder.
The fine powder is dried to remove any moisture residue that can affect the quality of the chipboard. Chipping, shredding, and drying create a uniform mixture that is mixed with an adhesive, which is normally a synthetic resin like urea formaldehyde. The resin adhesive strengthens the mixture and hardens the final chipboard sheets.
The mixture of powder and adhesive is flattened into rectangular shapes. The application of heat and pressure ensure that the finished paper is smooth and rigid.
Chipboard is referred to a "green" paper product due to being manufactured from 100% recycled paper waste. It is flexible with exceptional durability and capable of providing protection for products, materials, and instruments. A major benefit of chipboard, aside from its protective properties, is its cost, which is less than cardboard and corrugated sheets with the same or better strength.
The thickness of chipboard is measured in points, with each point being one one thousandth of an inch. It comes in several densities, which add to its multiple uses.
Flaps and handles are cut into the paperboard sheets by a trimmer or die cutters that perforate the sheets and score them. The cutters are made from half-cylinders with different cylinders for every type of box. They have sharp blades and rubber padding, which prevents the cutters from cutting too deeply into the sheets.
The sharp blades of the die cutters or trimmers cut out the shapes of the flaps and score the sheets for folding. Although the trimmers and cylinder die cutters are the most efficient method for shaping the flaps and scoring, simple die cutters similar to those used in a die press are also used for shorter production runs. They operate much like a stamping machine and cut the flaps and scoring with force and pressure.
A press condenses overlapping panels during the cutting and scoring process to level out their thickness. The sheets feed through the mechanism at 8 kilometers an hour or 5 miles an hour, processing over 90 boxes per minute. Any trimmed material is collected and recycled.
The bending or folding machine folds the boxes along the score lines. Glue or stitching connects the sections to form the completed box. The glue that is used is hygienic, an important feature for boxes used for the food industry. Staples are used for stitching boxes destined for heavy-duty applications and forming a tighter seal.
After the glue and stitching are applied, the completed boxes are piled and banded together.
In certain cases, boxes may need information printed on them to identify products, advertising, or other pertinent information regarding the box’s function and contents. Printing on boxes is a precision process that has to be carefully completed to avoid crushing the paperboard.
Feed rolls that send the boxes into the flexographic printing machine are made of soft material spaced properly for the depth of the sheets. The flexographic machine has printing plates for every color to be applied to the box. The plates are made of flexible photopolymer materials that are wound around a rotating cylinder. The process is very similar to that used by a letterpress.
Flexographic printing can apply a wide variety of colors, which are precision mixed and blended to meet the needs of the application or customer. Maintaining paperboard caliper or thickness is an essential part of ensuring the strength of the boxes.
The final step in the process is the inspection of the boxes before being shipped to customers. Special instrumentation is used to monitor glue placement and gap measurement. The system checks the amount and thickness of glue that has been applied and the size of the slots of the flaps. Each box is compared to the template used to produce the box.
All manufacturers pay close attention to their final products to ensure that the boxes live up to the organization’s standards and the high-quality materials they use. Although boxes are common types of containers that are found in manufacturing, retail, and homes, their assembly and construction require precision craftsmanship and close attention to detail.
Paperboard is one of the most popular forms of materials used for retail packaging due to the fact that it can be easily shaped, designed, configured, and engineered to offer a positive and aesthetic appearance to a product. Properly made paperboard is the first impression that customers get of a product or brand and is the method for presenting and displaying a product.
The many benefits of paperboard are further divided between the different grades of paperboard, which vary depending on the manufacturer. Understanding paperboard grades is an essential part of selecting the correct paperboard to fit the needs of a product and company. The various grades fluctuate widely in quality and price.
SBS is a brilliant white premium grade of paperboard that has the top ply of both sides of the board coated with clay, which allows for clear, crisp, and brilliant printing. The high quality of SBS comes from the hardwood fibers from which it is made. The internal plies of SBS are made of softwoods or blends of soft and hard-wood fibers.
In the manufacture of SBS paperboard, sulfate is used in the pulping of virgin hardwood. It is approved for use with food, has excellent foldability, is strong, and can be used in frozen applications. The many benefits of the SBS paperboard make it the most expensive of the paperboard grades.
CUK is made from unbleached virgin Kraft fibers that give it its brown color. It is made from softwoods, such as pine, with some hardwood fibers included in the top ply to create a smooth printable surface. The pine fibers are long and large, giving the paperboard excellent strength and tear resistance. The superior strength of CUK makes it ideal for beverage containers and heavy-duty packaging of tools and laundry detergents.
The strength and durability of CUK make it resistant to moisture. CUK is the strongest of all of the paperboard grades, is the most popular, and is less expensive than SBS.
UUK is a natural grade of brown paperboard made from a blend of softwood and hardwood. Recycled fibers are also blended with the tree fibers. It is a high-strength paperboard at a lower cost. The texture of UUK does not provide a surface for crisp printing or complex designs. It is ideal for storing hardware in moist conditions where heavy-duty use is required.
CRB is made of recycled fibers with a top ply of white fibers finished with a clay coating. There are many variations of this grade, which include CCN, WLC, Duplex, GB, and CCNB. It is a very low-strength grade of paper board and is ideal for lightweight items such as chips, crackers, cereal, or snacks.
URB is made from recycled newsprint and paper. It is a thick grade of paperboard that is used as a set up box or dividers. URB is the least expensive paperboard grade and provides the highest value for the money spent.
FBB is a multilayer paperboard made from chemical and mechanical pulp with mechanical pulp placed between layers of chemical pulp. The top ply is bleached chemical pulp, which is a low-density material with high stiffness. FBB is a virgin fiber paperboard that has purity for product safety. The combination of mechanical layers and chemical layers creates strong stiff sheets. When it is fully coated, it is printable with crispness and high resolution.
Regardless of the many positive qualities of FBB, it has the lowest strength of the grades of paperboard. By using variations in coatings and treatments, the strength of FBB can vary and be somewhat competitive with SBS. The amazing thing about FBB is its foldability. Boxes with attached lids open and close easily without any damage to the box’s scores.
Paperboard is the most common type of cardboard but is not the only type. Cardboard is a highly versatile material that comes in a wide variety of forms and can be structured to meet specific and specialized needs. The flexibility of cardboard allows it to be adjusted and adapted to different strengths, weights, widths, and endless functions.
Honeycomb cardboard is lightweight but durable. It has two outside panels that give it stability and strength as well as an expansive surface area. The strength of honeycomb cardboard makes it an ideal replacement for wood or plastic pallets. It can be manufactured in different strengths and sizes with an exceptional strength-to-weight ratio. In door manufacturing, honeycomb cardboard is used as filler for the door cavity.
The many thicknesses of honeycomb cardboard make it adaptable enough to be formed into resilient and durable boxes with corners secured with multi-ply cardboard. Honeycomb cardboard’s structure makes it possible for it to be impact resistant.
The variations in honeycomb cardboard include different sizes of the honeycombs as well as different cell sizes that range from 0.32 inches (8 mm) to 0.86 inches (22 mm). The heights of honeycombs can be from 0.23 inches (6 mm) up to 4.1 inches (104 mm).
Gray paperboard is a thick paperboard made from recycled paper pulp and gets its name from its color. It is widely used due to its stiffness. The surface of the paperboard is gray, while its other layers can be brown or gray. Gray paperboard is used for pad backing, rigid boxes, cartons, and bookbinding.
The strength of gray paperboard is due to the process used to manufacture it, which does not involve the use of glues or adhesive. The layers or plies of gray paperboard are connected by the board’s long fibers that are pressed together by heavy steel rollers.
Gray cardboard, like gray paperboard, is made using recycled paper and cardboard. It is smooth with good stiffness and slightly thicker than gray paperboard. The higher thicknesses of gray cardboard make it ideal as a replacement for laminated cardboard.
Cardboard boxes are the main choice for packaging, storage, and product display. Their flexibility makes them ideal for the protection and security of products while affording a pleasant appearance.
For every packing application, there is a box that easily and conveniently fits into the process. It is this characteristic of cardboard boxes that has led to innovations in packaging and shipping operations.
RSCs are typical shipping containers with flaps of equal size that meet when closed such that they can be taped and secured. The flaps at the end of the box bend inward and do not meet, while the flaps along the length of the box fold inward in such a fashion that their edges meet to be taped and secured.
FOL cardboard boxes follow the same pattern as RSC boxes with one slight adjustment. Unlike RSCs, the long outer flaps of a FOL cardboard box overlap when bent inward. This design provides for additional strength when the boxes are stacked and extra edge protection, which makes the box able to withstand rough handling.
An FTD-designed box has separate sections where one section fits inside the other section. The cover of an FTD completely covers the body of the box. The flaps on FTD boxes are stapled or taped. Their design provides compression strength when stacking heavy and large items.
The upper structure of a snap bottom box is similar to that of the RSC box. The flaps of the bottom of the box are cut and shaped such that they fold over each other. When the flaps are folded, they snap into slots and lock together. The design of snap bottom boxes makes them easy to assemble quickly.
A one piece folder cardboard box is a single unit that folds along score lines to form a box. The bottom of the box is a flat cardboard piece with four sides and flaps attached. When the flaps are closed, they raise the sides of the box to make its rectangular shape. As with the RSC box, the end flaps are short and do not touch, while the side flaps can overlap or meet at their edges, depending on the design of the box.
One piece folder cardboard boxes are designed for shipping single items such as iPads, books, video games, and other flat-profiled items. The flat surface of one piece folder cardboard boxes is ideal for printing logos, images, and instructions.
The self-locking cardboard box, or RELF (Roll End Lock Front) die-cut cardboard box, is very similar to the one piece folder. It is a single unit of cardboard that has been scored to fold into a box. The sides of the box have flaps attached at their long ends, while the ends of the box are double-width of equally scored sections.
To form a self-locking box, the sides of the box are folded upward with their flaps placed along the scoring of the ends of the box. The double-wide ends are brought upward such that one portion of the end folds over the extended flaps and is locked in place by a slot in the bottom of the box and tabs on the extended end piece.
The lids for self-locking boxes are formed using the same method and take the form of telescoping boxes where the folded lid fits over the folded box. The unique nature of self locking boxes eliminates the need for taping or gluing the sides. Tape is only used to seal the box.
Another form of self-locking box or RELF die-cut cardboard box has a lid attached to one of the long sides with extended flaps. The box is assembled like other self-locking boxes. The lid on one of the long sides folds up with flaps that slide inside the box and flaps that slide into the self-locked edges, as can be seen below.
The few boxes described here are only a sampling of the many boxes that are a vital part of the supply chain and shipping. Cardboard manufacturers constantly develop and create new designs for unique and unusual applications. Additionally, all manufacturers are ready and prepared to help their customers design boxes that perfectly fit their requirements.
Part of the reason for the wide use of chipboard is due to its multiple sizes and thicknesses. It can be shaped, configured, and manufactured into any form to fit the needs of a wide range of applications. Its main use is as packing for commercial and industrial products.
The sturdiness of chipboard makes it an ideal packing material for sensitive technical equipment that requires extra protection from vibrations and impact, which can damage the circuit boards of technological instruments during transport. Chipboard is used to provide structural integrity and stability.
Chipboard is used for bakery boxes due to its strength, durability, and flexibility, which prevent baked goods from being damaged. Additionally, the rounds placed underneath cakes are made from chipboard because it does not absorb moisture.
Tissue boxes are made from chipboard to prevent them from being crushed during transport.
Chipboard is used for beer cases due to its ability to withstand the weight of a case of beer, which can be over 20 lbs (9 kg).
Retail displays present products using attractive displays that show the product in a positive and accessible way. Displays have to be lightweight yet sturdy enough to withstand constant use. Chipboard is used to meet the many factors required by retail displays and is resilient enough to last.
A very common use for chipboard is as backing for pads of paper, these backings have the proper consistency and strength to support paper during use. Thin chipboard that can be cut to fit the shape of any pad is durable and flexible as a backing. Additionally, chipboard is used as backing in picture frames and shipping envelopes.
Chipboard is used in furniture as a structural component that can be covered with wood or veneer. It is used in the sides and backs of chairs and couches, adding stability and support.
The inability of chipboard to absorb moisture is one of the main reasons it is used for the delivery of fast foods. It does not become soggy and helps retain the flavor and smells of the food.
The eight products described above are only a small sampling of the many uses for chipboard. Its ability to be configured and manufactured in a variety of shapes and sizes enables it to fit the needs of any application regardless of how demanding or rigid.
The introduction of the cardboard box during the first industrial revolution radically changed the nature of the packaging industry. Sir Malcolm Thornhill introduced the first cardboard box in 1817, which first appeared in the United States in 1895, where they took off and became common packaging containers.
Small cardboard boxes of lighter paperboard became popular at the beginning of the 20th century to store and sell breakfast cereal. This use of cardboard boxes has grown rapidly to the point that most products are sold using some form of cardboard box.
Even though they are just paper and starch, cardboard boxes are strong, pliable, and moisture-resistant. They are the ideal method for shipping, protecting, promoting, and storing items of all shapes, sizes, configurations, and forms. With the proper surface finish, they can have an endless number of images and displays printed on them, including colorful graphics, creative designs, and entertaining pictures.
The main reason for the rapid rise of cardboard boxes is their cost, which is far lower than their predecessors. Cardboard boxes can be manufactured to fit the budget of any company regardless of its size. They are a perfect cost-effective way of getting a brand noticed. The low cost of cardboard boxes is related to the low cost of labor and materials in their production. Additionally, over 80% of all cardboard is recyclable and reusable, which further lowers its cost.
Sustainability has become a major push in 21st-century industry and manufacturing with the goal of preserving our environment for future generations. Cardboard boxes smoothly fit into the goals and focus of sustainability since, at the end of their life cycle, they can be reprocessed to make more boxes.
The cardboard box industry is one of the largest industries in the United States, with a value of over $60 billion. The industry takes pride in the fact that all of its products are made from raw materials found in the United States and use American workers.
Over the years, engineers and designers have continued to expand the use of cardboard boxes by creating innovative and practical designs. Using the many types of paperboard, and cardboard, manufacturers have been able to produce cardboard boxes to fit any shipping, packaging, and storage application.
The main reason that cardboard has achieved increasing popularity is due to the fact that it does not end up in a landfill or garbage dump. Trash collection companies have developed special procedures to segregate cardboard materials such that they can be bundled and shipped to producers for reprocessing.
Of the many things that are consumed and used every day, cardboard boxes are the most environmentally friendly tool. Over 80% of all cardboard produced can be reused without any restrictions. Box manufacturers can take any form of cardboard and reprocess it to make products that are comparable to virgin products. The fact that cardboard can be reused endlessly without any degradation makes it the ideal product for preserving and saving the environment.
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