This article is an in-depth guide to how cardboard boxes are made.
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A cardboard box is a type of container used for shipping, constructed from layers of robust paper thicker than 0.01 inch (0.25 mm). "Cardboard" is a broad term encompassing various solid, sturdy papers used for making boxes. This category includes different styles of paper containers like corrugated and chipboard boxes.
Cardboard boxes come in various forms, created by folding, cutting, and molding sheets of heavy-duty layered paper.
Chipboard boxes are part of the recycling sector, manufactured from reclaimed cardboard, paper scraps, and sawdust, which are processed into solid panels. Although similar in appearance to cardboard, chipboard is made from recycled materials pressed and glued into dense sheets.
Designed for durability and protection, cardboard boxes are lightweight but robust enough to safeguard items. They are ideal for storing and transporting products like apparel and toys, as their sturdy sides offer impact resistance.
Cardboard sheets are also utilized as dividers or padding inside larger, more durable containers.
The widespread use of cardboard boxes is largely due to their recyclability, which makes them a cost-effective alternative to other container types. The paper layers in cardboard can be shredded, treated, and reprocessed into new rolls to create recycled paper or chipboard.
Approximately 90% of all goods are transported using cardboard boxes, with more than 88% of these boxes being produced from recycled materials. Producing cardboard boxes from new materials is energy-intensive and involves the use of numerous trees. In contrast, using recycled materials to make cardboard boxes significantly reduces energy consumption and prevents these materials from ending up in landfills, where they could potentially release harmful toxins.
Cardboard boxes are available in a wide range of shapes, sizes, and designs to accommodate different product requirements. Typically, these boxes are crafted from recycled paper or tree pulp. The resulting paperboard is made by layering treated and pressed pulp to form a sturdy material.
The process of manufacturing cardboard boxes starts with robust papers derived from tree pulp. The tree fibers undergo various treatments to produce the durable raw materials needed for box production.
Pulping is the technique used to produce paper for paperboard. This process involves breaking down raw materials into individual fibers, known as paper pulp. The goal of pulping is to remove lignin from the fibers while preserving the fiber structure. Various methods, including chemical, mechanical, and biological techniques, are employed for pulping, with all requiring approximately 26.4 gallons (100 liters) of water to create one kilogram of paper.
Mechanical pulping is a physically intensive method that separates fibers without the use of chemicals. In this process, wood chips are ground by stones and mixed with water to create pulp. Mechanical pulping offers high yield and minimal pollution but results in lower fiber strength.
Chemical pulping combines chemical and mechanical processes, where wood chips are cooked and ground to produce cellulose fibers. This method provides a more effective separation, yielding high-quality paper.
Raw pulp contains lignin, which gives it a dark brown color. To produce paperboard, the pulp must undergo a bleaching process to remove the lignin and lighten the color. This bleaching step is essential for both virgin and recycled fibers, as it also eliminates any residual chemicals from recycled cardboard.
Bleaching methods vary based on the pulp's color, the chemicals used, and the treatment types. The primary bleaching techniques include delignification, oxidation, and reduction, all involving chemical reactions.
During the final processing stage, the pulp is passed through blades that flatten the fibers and create fibrillated ends to enhance bonding and strength. Fillers are incorporated to increase the pulp's density and opacity. At this point, the pulp is prepared for the paper machine.
The paper machine utilizes a series of mechanisms to dry the pulp by passing it through rotating wires and belts that remove the water. Pressure and heat are applied to eliminate any remaining moisture before the paper is wound onto large rolls.
Paperboard is created by layering pulp that is sprayed with water onto a mesh screen to form a mat. This process builds up the fibers in the pulp, enhancing the strength and solidity of the paperboard. Each paperboard type or grade is meticulously blended to ensure it meets specific grade requirements.
After the mat is formed, the excess water needs to be removed. Initially, the mat is passed over a foundation screen where about 20% of the water drains out by gravity. The mat then continues through sponge rollers that press out additional water. Once sufficiently squeezed, the mat is ready for the final drying phase, where it is stretched and heated to complete the drying process. The resulting moisture content of the paperboard is around 5%.
The completed paperboard is cut into various widths and rolled into large rolls for shipment to box manufacturers. These different widths allow for the production of boxes in various sizes, shapes, and configurations to meet specific customer needs.
Once the paperboard is dried and completed, it may undergo additional processing, which includes applying a polymer coating. This coating is made from melted pellets that are extruded as a very thin layer onto the paperboard’s surface. Prior to coating, a starch solution is applied to help bind the fibers and enhance the board’s strength.
Before the coating is applied, the paperboard is pressed between steel rollers to create a smooth surface, improve its strength, and ensure uniform thickness and density. The coating can be applied to one or both sides of the board and is spread evenly. After coating, the paperboard is dried and wound onto a steel core. The large reels are then cut into various widths according to customer requirements. The paperboard can be wrapped and bound as rolls or cut into sheets of different sizes as needed.
The final paperboard product has a smooth, glossy finish similar to that found on milk or juice cartons.
Once the paperboard is completed, it is sent to box manufacturers where it is transformed into various types of boxes according to customer specifications. During this conversion, features like handles, flaps, and slits are added, and the paperboard is scored to facilitate folding into different box shapes.
The methods used to turn paperboard into lightweight cardboard boxes can differ depending on the manufacturer.
Large rolls of paper are shipped to the box manufacturing facility, with widths varying to accommodate the sizes of boxes to be produced.
Kraft paper, named after the German word for "strength," is crafted from softwood trees with long fibers, such as pine, spruce, or fir. These long fibers contribute to Kraft paper's resistance to tearing and bursting. Its color can range from brown to yellowish, depending on the tree species used. For example, paper made from spruce, pine, and silver birch trees tends to be a darker brown, while paper from other trees appears more yellowish. Additionally, the quality and color of Kraft paper can vary based on the geographical origin of the trees.
In the manufacturing process, once the first liner is applied, Kraft paper is affixed to the opposite side of the fluted layer. This basic configuration is known as single-wall corrugated board, as illustrated in the image on the left. More complex variations may include two layers of flutes and two liners of Kraft paper, as shown on the right. The width of the flutes can also vary based on the box design.
Kraft paper has long been utilized in making corrugated boxes due to its durability and resistance to tearing. It is also used to produce rigid and sturdy cardboard boxes. Its textured and porous surface makes it particularly suitable for printing and crafting display boxes.
Unlike other types of paper used for cardboard, Kraft paper has a distinctive rustic and raw look. Its versatility provides designers with a broad range of options for packaging and box design.
Chipboard is a type of thick, rigid paper made from recycled paper, wood residues, paper scraps, and sawdust. These materials are combined into a slurry with urea formaldehyde, similar to paperboard production. The mixture is then pressed and heated to create sturdy panels. Chipboard is widely used in packaging for producing boxes, padding, and other shipping materials.
While "chipboard" and "cardboard" are often used interchangeably, they refer to distinct materials. Chipboard is made from entirely recycled paper that is compressed into solid panels, whereas cardboard or corrugated sheets are constructed from layered paper. Chipboard is highly versatile and durable, providing comparable strength to that of cardboard and corrugated materials.
Chipboard is available in various densities and thicknesses, making it a robust paper stock. It serves as an effective alternative to corrugated cardboard and is used to manufacture cartons, boxes, and sheets in various sizes and strengths.
Chipboard manufacturing involves compressing small pieces of waste paper, cardboard, and sawdust with adhesive to create strong and durable panels. The raw materials for chipboard come from discarded scraps from various production processes or collected from recycling bins.
Typically, chipboard is brown and known as Kraft chipboard, although varieties made from newspaper can have a grayish hue. In certain processing methods, chipboard is coated with clay, resulting in a thin, white surface.
Chipboard is made from leftover waste materials from other manufacturing processes, as well as scrap cardboard, paper, and packaging materials collected through recycling. To be suitable for chipboard production, these waste materials must first be processed into a granular form.
To achieve the desired texture, the raw materials are processed through a shredder or chipper, which grinds and pulverizes them into a fine powder.
The fine powder is dried to eliminate moisture that could impact the chipboard's quality. The dried material is then mixed with an adhesive, typically a synthetic resin such as urea formaldehyde. This resin binds the mixture together, enhancing its strength and allowing the chipboard sheets to harden effectively.
The mixture of powdered material and adhesive is compressed into rectangular shapes. Applying heat and pressure during this process ensures that the resulting chipboard is smooth and rigid.
Chipboard is considered a "green" paper product because it is made entirely from recycled paper waste. It offers flexibility and exceptional durability, making it effective in protecting various products, materials, and instruments. Additionally, chipboard is cost-effective, often being less expensive than cardboard or corrugated sheets while providing comparable or even superior strength.
Chipboard thickness is measured in points, where each point equals one thousandth of an inch. It is available in various densities, enhancing its versatility for different applications.
Flaps and handles are cut into paperboard sheets using trimmers or die cutters, which perforate and score the sheets. These cutters consist of half-cylinders, each designed for specific box types, equipped with sharp blades and rubber padding to prevent excessive cutting into the sheets.
The die cutters or trimmers feature sharp blades that cut out flap shapes and score the sheets for folding. While trimmers and cylinder die cutters are highly efficient for shaping and scoring, simpler die cutters, akin to those used in die presses, are employed for shorter production runs. These machines operate similarly to stamping presses, using force and pressure to cut and score the paperboard.
A press is used to compress overlapping panels during the cutting and scoring stages, ensuring uniform thickness. The sheets move through the press at speeds of up to 8 kilometers per hour (5 miles per hour), processing more than 90 boxes per minute. Trimmed excess material is collected and recycled.
The folding machine bends the boxes along the pre-scored lines. Sections are then joined using glue or staples to create the finished box. Hygienic glue is used for boxes intended for the food industry, while staples are employed for heavy-duty boxes to ensure a stronger seal.
Once glued and stitched, the completed boxes are stacked and banded together for further handling.
In some cases, boxes require printing to display product information, advertising, or other relevant details about their function and contents. This printing process must be carefully managed to prevent damage to the paperboard.
Feed rolls, made from soft materials and spaced according to the sheet depth, guide the boxes into the flexographic printing machine. This machine uses printing plates for each color applied to the box. These plates are flexible photopolymer materials wrapped around rotating cylinders, operating similarly to a letterpress.
Flexographic printing allows for a broad range of colors, which are precisely mixed and blended to meet specific requirements. Maintaining the paperboard's caliper or thickness is crucial for ensuring the boxes' strength and durability.
The final stage of production involves inspecting the boxes before they are shipped to customers. Specialized equipment is used to verify the accuracy of glue application and flap measurements. This system assesses the amount and thickness of glue used and checks the dimensions of flap slots, comparing each box to the production template.
Manufacturers meticulously review their finished products to ensure they meet organizational standards and reflect the high-quality materials used. Despite their common presence in manufacturing, retail, and homes, the assembly and construction of boxes demand precise craftsmanship and meticulous attention to detail.
Paperboard is a favored material for retail packaging because it can be easily shaped, designed, and customized to enhance the visual appeal of a product. Well-crafted paperboard creates a strong first impression for customers, serving as the primary method for presenting and showcasing products.
The advantages of paperboard are categorized by different grades, which can vary based on the manufacturer. Understanding these grades is crucial for selecting the appropriate paperboard that meets the specific needs of a product and company. The quality and cost of paperboard grades can vary significantly.
SBS (Solid Bleached Sulfate) is a high-quality, bright white paperboard known for its premium finish. Both sides of the board are coated with clay, resulting in clear, crisp, and vibrant printing. SBS is valued for its superior quality, derived from its use of hardwood fibers, while its internal layers are made from softwoods or a mix of soft and hardwood fibers.
SBS paperboard is produced using sulfate pulping of virgin hardwood, making it suitable for food contact, highly foldable, and strong enough for frozen applications. Its numerous advantages make SBS the most expensive among paperboard grades.
CUK (Coated Unbleached Kraft) is crafted from unbleached virgin Kraft fibers, giving it a distinctive brown color. It primarily uses softwoods, like pine, with some hardwood fibers in the top layer to provide a smooth surface for printing. The long, robust pine fibers contribute to CUK's excellent strength and tear resistance, making it well-suited for beverage containers and heavy-duty packaging for tools and laundry detergents.
CUK's durability also makes it resistant to moisture. It is the strongest of the paperboard grades, widely used, and more affordable compared to SBS.
UUK (Unbleached Uncoated Kraft) is a natural brown paperboard made from a mix of softwood and hardwood fibers, including recycled fibers. It offers high strength at a lower cost. However, its texture is not suited for detailed printing or intricate designs. UUK is well-suited for storing hardware in damp environments and for applications requiring heavy-duty performance.
CRB (Coated Recycled Board) is composed of recycled fibers with a top layer of white fibers and a clay coating. This grade includes several variations such as CCN, WLC, Duplex, GB, and CCNB. CRB is a low-strength paperboard, making it suitable for lightweight products like chips, crackers, cereal, and snacks.
URB (Uncoated Recycled Board) is produced from recycled newsprint and paper. It is a thick grade of paperboard often used for setup boxes or dividers. URB is the most cost-effective paperboard grade, offering excellent value for the money.
FBB (Folding Box Board) is a multilayer paperboard made from a combination of chemical and mechanical pulps. Mechanical pulp is sandwiched between layers of chemical pulp, with the top ply consisting of bleached chemical pulp. This low-density material provides high stiffness and ensures product safety with its virgin fiber composition. The blend of mechanical and chemical layers results in strong, rigid sheets that, when fully coated, allow for crisp and high-resolution printing.
Despite its many advantages, FBB has the lowest strength among paperboard grades. However, variations in coatings and treatments can enhance its strength, making it somewhat competitive with SBS. One of the notable features of FBB is its excellent foldability; boxes with attached lids can be opened and closed smoothly without damaging the score lines.
While paperboard is one of the most common forms of cardboard, it is not the only type. Cardboard is an exceptionally versatile material available in various forms, allowing for customization to meet specific and specialized requirements. Its flexibility enables adjustments in strength, weight, width, and functionality to suit a wide range of applications.
Honeycomb cardboard is both lightweight and durable, featuring two outer panels that provide stability and strength, along with a broad surface area. Its robust nature makes it an excellent alternative to wood or plastic pallets. Honeycomb cardboard can be produced in various strengths and sizes, offering an exceptional strength-to-weight ratio. In door manufacturing, it serves as a filler for door cavities.
Available in various thicknesses, honeycomb cardboard can be shaped into sturdy and resilient boxes with corners reinforced by multi-ply cardboard. Its unique structure provides impact resistance, enhancing its durability.
Honeycomb cardboard comes in different configurations, with cell sizes ranging from 0.32 inches (8 mm) to 0.86 inches (22 mm) and honeycomb heights from 0.23 inches (6 mm) to 4.1 inches (104 mm).
Gray paperboard is a robust type of paperboard made from recycled paper pulp, characterized by its gray color. Known for its rigidity, it is commonly used in applications such as pad backing, rigid boxes, cartons, and bookbinding. The surface of gray paperboard is gray, with inner layers often appearing brown or gray as well.
Its strength arises from the manufacturing process, which does not involve adhesives or glues. Instead, the layers or plies of gray paperboard are bonded by the long fibers of the board, which are pressed together using heavy steel rollers.
Gray cardboard, similar to gray paperboard, is produced from recycled paper and cardboard. It features a smooth surface with excellent rigidity and is slightly thicker than gray paperboard. The increased thickness of gray cardboard makes it a suitable substitute for laminated cardboard.
Cardboard boxes are the preferred option for packaging, storage, and product display due to their adaptability. They offer excellent protection and security for products while maintaining an attractive appearance.
Cardboard boxes come in various designs to suit every packing need, making them integral to innovations in packaging and shipping processes. Their versatility has driven advancements in how products are packaged and transported.
RSC (Regular Slotted Containers) are standard shipping boxes with flaps of equal size that align when closed, allowing them to be taped and secured. The end flaps fold inward without meeting, while the side flaps fold inward so their edges align for taping and securing.
FOL (Full Overlap) cardboard boxes are similar to RSC boxes but with one key difference: the long outer flaps overlap when folded inward. This design enhances the box's strength when stacked and provides additional edge protection, making it more resilient to rough handling.
FTD (Full Telescope Design) boxes feature a design where one section fits into another, with the cover fully enclosing the box body. The flaps are secured with staples or tape. This design offers excellent compression strength, making it suitable for stacking heavy or large items.
Snap bottom boxes have a similar upper structure to RSC boxes but with a distinctive bottom design. The flaps are cut and shaped to fold over each other and snap into slots to lock securely. This feature allows for quick and easy assembly of the box.
A one-piece folder cardboard box is designed from a single sheet that folds along pre-scored lines to create the box. The bottom of the box is a flat piece with four sides and attached flaps. When folded, these flaps raise the sides to form a rectangular shape. As with RSC boxes, the end flaps are shorter and do not meet, while the side flaps either overlap or align at their edges based on the specific box design.
One-piece folder cardboard boxes are typically used for shipping individual items like iPads, books, video games, and other flat or thin objects. Their flat surface is perfect for printing logos, images, and instructions, making them a versatile choice for various packaging needs.
The self-locking cardboard box, also known as the RELF (Roll End Lock Front) die-cut box, resembles the one-piece folder but with distinctive features. It consists of a single piece of cardboard that is scored to fold into shape. The sides have long flaps attached, and the ends are made from double-width, equally scored sections.
To assemble a self-locking box, the sides are folded upward, and their flaps are aligned with the scoring on the box's ends. The double-wide end sections are then folded up, with one part of the end overlapping the extended flaps. This configuration is secured by slots in the box's base and tabs on the end pieces.
The lids for self-locking boxes are created in a similar manner, resulting in telescoping lids that fit over the folded box. The innovative design of self-locking boxes eliminates the need for tape or glue to secure the sides; only tape is required to seal the box.
Another variation of the self-locking or RELF die-cut box features a lid attached to one of the long sides with extended flaps. As with other self-locking boxes, it is assembled by folding the sides and positioning the flaps. The lid on the long side folds up, with flaps sliding into place inside the box and engaging with the self-locked edges.
The examples of boxes mentioned here represent just a small portion of the diverse range used in supply chain and shipping processes. Cardboard manufacturers continuously innovate and design new boxes for specialized and unique applications. Moreover, these manufacturers are always available to assist customers in designing boxes that meet their specific needs perfectly.
Chipboard's versatility in various sizes and thicknesses contributes to its extensive use. It can be shaped and customized to suit a broad array of applications. Primarily, chipboard is utilized for packaging commercial and industrial goods.
Chipboard's durability makes it an ideal packing material for sensitive technical equipment, offering protection against vibrations and impacts that could damage electronic components during transport. It provides essential structural integrity and stability.
In the bakery industry, chipboard is used for boxes to safeguard baked goods from damage. Its strength and flexibility also make it a suitable material for cake boards, as it does not absorb moisture.
Chipboard is commonly used for tissue boxes, ensuring they remain intact and do not collapse during shipping.
Beer cases often use chipboard due to its ability to support the weight of a case, which can exceed 20 lbs (9 kg), making it a robust choice for packaging.
Retail displays benefit from chipboard's lightweight yet sturdy nature. It provides the necessary strength and resilience to withstand frequent handling while presenting products attractively.
Chipboard is also used as backing for pads of paper, offering the right balance of strength and flexibility to support the paper. It is also commonly found as backing in picture frames and shipping envelopes.
In furniture manufacturing, chipboard serves as a structural component, often covered with wood or veneer. It is used in the sides and backs of chairs and couches, adding stability and support.
Its resistance to moisture makes chipboard a preferred choice for fast-food packaging, as it prevents sogginess and helps retain the food's flavor and aroma.
The diverse applications of chipboard, as illustrated above, showcase its versatility. Its ability to be customized in various shapes and sizes makes it suitable for a wide range of demanding uses.
The advent of the cardboard box during the first industrial revolution marked a significant shift in the packaging sector. Introduced by Sir Malcolm Thornhill in 1817, this innovation arrived in the United States in 1895 and quickly became a staple for packaging.
By the early 20th century, smaller cardboard boxes, made from lighter paperboard, became popular for packaging breakfast cereals. This trend grew rapidly, and today, cardboard boxes are prevalent in the packaging of a vast array of products.
Despite being composed primarily of paper and starch, cardboard boxes are remarkably sturdy, flexible, and resistant to moisture. They are perfect for shipping, safeguarding, showcasing, and organizing products of various shapes and sizes. With the right surface treatment, these boxes can feature an extensive range of prints, including vibrant graphics, innovative designs, and engaging images.
The swift popularity of cardboard boxes can be attributed primarily to their affordability, which is significantly lower than previous packaging options. These boxes can be produced to suit any company's budget, making them an economical choice for enhancing brand visibility. The reduced cost of cardboard boxes is linked to the inexpensive labor and materials used in their production. Furthermore, more than 80% of cardboard is recyclable and reusable, contributing to its cost-effectiveness.
In the 21st century, sustainability has emerged as a crucial focus in industry and manufacturing, aiming to protect our environment for future generations. Cardboard boxes align perfectly with these sustainability goals because they can be recycled and repurposed into new boxes at the end of their lifecycle.
The cardboard packaging sector stands as one of the most significant industries in the U.S., valued at over $60 billion. This industry emphasizes its commitment to utilizing domestic raw materials and employing American workers for its production processes.
Engineers and designers have consistently pushed the boundaries of cardboard box usage through creative and functional designs. By leveraging various types of paperboard and cardboard, manufacturers have developed solutions tailored to diverse shipping, packaging, and storage needs.
The growing popularity of cardboard is largely attributed to its recyclability. Unlike many other materials, cardboard doesn't often end up in landfills. Waste management companies have established specialized processes to sort cardboard, allowing it to be collected, bundled, and sent to manufacturers for recycling.
Among the countless everyday items, cardboard boxes stand out as exceptionally eco-friendly. More than 80% of all cardboard manufactured is recyclable without limits. Manufacturers are able to repurpose any type of cardboard to produce items that match the quality of new products. The endless recyclability of cardboard, without loss of quality, makes it an ideal choice for environmental conservation and sustainability.
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