This article contains a description of mailing tubes, how they are made, and their use.
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A mailing tube is a sturdy, solid, and durable cardboard container designed for shipping long slender devices and products or rolled up maps, banners, and posters. The indestructible exterior of mailing tubes offers protection and security for its contents as well as easy handling.
Mailing tubes come as triangular prisms, cylindrical tubes, and square prisms. They are made of highly durable and sturdy paperboard or corrugated board. Cylindrical mailing tubes have sheets of Kraft and test paper wound around a mandrel to form them, while triangular and square tubes are made like boxes and are foldable. Regardless of the tube shape, all mailing tubes are designed to withstand the handling and stress associated with mailing and shipping.
The raw materials for mailing tubes are Kraft paper, test paper, and paperboard that are glued or folded into tube shapes. The choice of the types of materials is based on how durable the mailing tubes need to be since they can contain precious and valuable items or confidential blueprints and drawings. Mailing tubes are sealed with plastic or aluminum caps, cardboard folded over, or tape. The type of seal is dependent on the items being shipped and the security requirements.
Packing and shipping materials have developed and changed over the years to meet the requirements of technology and different shipping methods. Initially, long items to be shipped were placed in boxes or wrapped in paper with the hope that they would not be damaged in transit.
Modern mailing tubes have been perfected and improved to meet the demands of modern shipping. They come in varying lengths, widths, shapes, and materials to exactly meet the needs of businesses. The sturdiness and durability of mailing tubes make it possible to use them successfully. Even when they have outlived their usefulness, the raw materials in mailing tubes can be recycled and repurposed.
Telescoping mailing tubes, also known as adjustable tubes, can have their length extended to accommodate different sized documents, maps, banners, parts, and posters. They have a spiral wound construction with thick heavy duty cardboard walls. Telescoping mailing tubes are a tube within a tube where the inside tube easily slides in and out of the exterior tube to match the length of the item to be shipped.
The durability and sturdiness of telescoping mailing tubes make them ideal for shipping metal rods, long industrial parts, and other heavy elongated objects. They allow for instant customizing of the tube to match any length. To prevent the tube from retracting, tape or a label is placed over the connection between the tubes.
Snap seal mailing tubes or crimped end mailing tubes eliminate the need for tape and end plugs. To load an item into a snap seal mailing tube, one end of the tube must be crimped while the other end is left open. Whatever is to be shipped can easily be slid into the open end. Once fully loaded, the open end can be crimped. The simple crimping process can effortlessly seal snap seal mailing tubes. Of the many types of mailing tubes, snap seal mailing tubes are the most economical but still have the same strong rigid structure found in other mailing tubes.
The easy to open and close ends of snap seal mailing tubes save time and forms a tight firm seal that remains closed. Snap seal mailing tubes are made of wound Kraft paper that is glued on a mandrel. They come in lengths of a few inches up to three or four feet.
The manufacturing of triangular mailing tubes is similar to that used to produce boxes. They are die cut with flaps to be folded and glued. The main benefit of triangular cardboard mailing tubes is that they lay flat and can be stacked without rolling or shifting. In the majority of cases, they are made of corrugated board with flaps and come in a wide variety of lengths from ones that are less than a foot up to ones that are three to four feet.
The three sides of triangular mailing tubes also come in varying widths, which the manufacturer can adjust to fit the specific requirements of a product. The three diminishes of a triangular mailing tube are its length, the width of the sides, and the size of its opening, each of which can be customized.
Unlike wound cylindrical tubes, triangular mailing tubes have a choice of types of openings. With one type, the tube opens at both ends with three flaps that overlap to seal the tube. Items to be shipped are placed in the tube much like a cylindrical tube by being slid in one end.
The other configuration of triangular mailing tubes is similar to a box with flaps and a lid. With this opening type, one of the sides of the tube serves as the lid. The ends of the tube are much like the ends of a box and are tightly sealed and glued. Items to be shipped are placed in the side of the tube after which the lid is closed and taped.
The different configurations of openings of triangular mailing tubes make it possible to adjust the tube to precision fit the needs of a product. It is a kind of flexibility that has led to the popularity of triangular mailing tubes.
Plastic plug mailing tubes are an alternative to snap mailing tubes and have a plug that fits into the end of the tube to replace the snap configuration. They are manufactured using the same method as snap mailing tubes by being wound on a mandrel with overlapping layers of Kraft paper. Plastic plug mailing tubes come in several different designs, which vary depending on the type of plug being used.
The variations in plastic plug mailing tubes are in relation to the sealed end of the tube, which can be closed with a permanent metal plug, a flap of cardboard, a permanent plastic plug, or a removable plug. The type of end of a plastic plug mailing tube is dependent on the manufacturer and the tube’s design.
Plastic plug mailing tubes come in a wide assortment of lengths and diameters, with lengths ranging up to several feet and diameters from a few inches up to close to ten inches. Plugs for the tubes are designed to be forced into the tube such that they form an impenetrable seal to keep out dust, dirt, water, and other materials.
An alternative to plastic plug mailing tubes is metal plug mailing tubes, which are more permanent and durable. Metal plugs can take different formats with ones that are similar to plastic plugs and can be wedged into the end holes of mailing tubes. Another type of metal plug is self-gripping or self-locking which is permanently attached to the ends of a mailing tube after being inserted using a mallet.
Metal plug mailing tubes have one accessible end with the other end permanently secured. The plugs are made of highly durable heavy duty materials that make them capable of being used multiple times and come in diameter sizes from a little over an inch up to nearly nine inches.
In the mailing tube packaging industry, plastic, metal, or other forms of plugs are also known as enclosures and are specifically designed to meet the varying shipping needs of a wide variety of applications.
Curled end mailing tubes are also referred to as rolled edge canisters. They come in two or three piece adjustable or telescoping tubes or single piece tubes. In one design of a curled end mailing tube, one end of the tube has its circumference folded inward with a round piece of heavy paper or cardboard glued to the top of the curled ends.
In a two piece adjustable curled end mailing tube, the telescoping piece is curled and sealed with a piece of paper or cardboard. A three piece curled end adjustable curled end mailing tube has a single piece tube without either end sealed and fits into two curled end tubes that have one end curled and sealed.
The three varieties of curled end mailing tubes can be seen in the diagrams below.
Paper cap mailing tubes are one of the oldest forms of mailing tubes with ends that are paper shaped cups placed over the ends of the tube. The end caps are made of sturdy Kraft paper, with one end glued or stapled while the other can be slipped off to load the tube.
A square mailing tube has the same structure as a box and is die cut. They can be open on one end like a long box or be open on the side like a traditional box. Like triangular mailing tubes, square mailing tubes sit flat and can be easily stacked without concern for them rolling or shifting. They can be made from white coated paperboard or corrugated paper board either of which are durable and capable of withstanding the rigors of shipping.
After being shaped, square mailing tubes are shipped flat to be folded by the customer, which can be completed swiftly and secured with tape or glue.
Kraft paper is one of the main components in the manufacture of corrugated cardboard and paperboard cardboard. In both cases, it serves as the exterior layer of the board due to its weight, thickness, strength, and impenetrable surface. Kraft paper gives boxes and tubes exceptional stiffness and rigidity such that they maintain their shape.
The process for making Kraft paper is pulping, where the fibers of trees are pulverized to form a pulp paste or slurry. Completed and processed Kraft paper may be coated or laminated to enhance its strength and protective properties.
All paper begins with wood pulp that is transformed from chips to wood pulp. Initially, the wood chips are mixed with hot water, sodium hydroxide, and sodium sulfide and placed under pressure in containers called digesters. Each batch of the pulp can range in size from 10 tons to 20 tons. The mixture of chemicals and water breakdown the lignin, hemicellulose, and cellulose. For the pulping process to be successful, the lignin has to be separated from the cellulose since lignin does not make good paper.
In wood, lignin is the material that holds the wood fibers together and is 25% of the structure of a tree. The rest of the wood includes 50% water and 25% cellulose fiber. The pulping process aims to get to the cellulose fibers and separate them from the lignin.
At the beginning of the pulping process, bark, large wood chips, and other portions of the tree that are not good for the pulping process are removed. Once the acceptable chips are washed and cleaned, they are sent to the digester for chemical treatment. It is in the digester that the lignin is dissolved and removed from the wood chips leaving the cellulose fibers.
Regardless of the efficiency of the digester, there are still contaminants present in the fibers that have to be removed, which is accomplished in the steps of the bleaching station. The pulp from the digester is washed with bleach and water in a series of steps to remove any possibility of remaining lignin. As the pulp moves through the bleaching process, it becomes whiter and whiter, making the pulp extremely bright.
At the end of the bleaching process, the pulp is sent on to form Kraft paper or paperboard.
Prior to being put through the paper making machine, additives are injected into the pulp to enhance its strength. The main additive for Kraft paper is sulfate. The pulp is poured onto a wire screen where the water from the pulping process drains away and the fibers mat. To further the drying process, the layers of paper pass through a series of rollers and dryers that squeeze, press, and smooth the paper, which is referred to as calendaring.
At the end of the initial drying process, 84% of the water content of the paper is removed. To further bond the paper fibers, the paper is steam heated to finish the drying process before being collected on steel cylinder rollers.
There are many varieties of Kraft paper, not all of which are used to manufacture cardboard mailing tubes. Only the strongest and most resilient forms of Kraft paper are chosen to make paperboard and corrugated board for the manufacture of mailing tubes.
Virgin natural Kraft paper is used to make cardboard boxes and mailing tubes. It is tear resistant with superior bursting strength and can be applied in layers. Virgin natural Kraft paper is used to make paperboard and corrugated board.
Recycled Kraft paper is not as strong as virgin Kraft paper and is used for the inner layers of cardboard.
Clay coated Kraft paper is used to produce boxes and comes in white, glazed, grease resistant, and ribbed forms.
Laminated Kraft paper has a coating added to enhance the strength of the paper and give it consistency. It has dimensional stability and exceptional stiffness.
This short list of Kraft papers is only a sampling of its many types. It is used to make paper bags, backings for frames, the manufacture of steel, and specialized packing materials. The ones listed above are commonly used to manufacture mailing tubes.
The two types of cardboard mailing tubes are manufactured using different processes and methods. Cardboard cylinder production requires a unique set of steps that are completely different from the techniques used to make square and triangular mailing tubes, which are produced using the same methods as those used to make boxes.
Square and triangular mailing tubes are produced in sheets that are cut from corrugated cardboard or paperboard. Cardboard cylindrical tubes are made from sheets of Kraft paper that are glued and wrapped around a mandrel.
The first step in manufacturing cylindrical mailing tubes is to cut large rolls of Kraft paper into narrow widths. Several rolls may be placed together to be fed onto the mandrel for the shaping of the sides of the mailing tube. In the majority of cases, thick durable Kraft paper is used to make the tube rigid and firm.
The thickness of the walls of the tube are determined by the number of times the Kraft paper is wound onto the mandrel and the thickness of the paper.
Prior to the paper ribbons being wrapped around and fed by the winder onto the mandrel, they pass through an adhesive bath, which is a cascading gluing system that pumps glue onto each ply or layer of paper. As the access glue accumulates, it is wiped off and sent back into the system.
The winder gathers the plies of paper and wraps them around the mandrel. The ribbons of paper are pulled forward continuously to form an endless spirally wound paper tube. The interplay between the mandrel, the winder, and the adhesive are the main aspects of the tube forming process.
The ribbons from the paper rollers are wound onto the mandrel, whose circumference is the inner diameter (ID) of the mailing tube. Prior to the glue soaked ribbons being wound around the mandrel, an inner unglued liner is applied to the mandrel such that the glued ribbons do not stick to the mandrel, and the wound tube can easily move down to the cutting process. The number of times the paper ribbons are wound around the mandrel determines the thickness of a cylindrical mailing tube. Included in the wall thickness is the thickness of the Kraft paper.
The wrapping and winding of the ribbons around the mandrel is a continuous process. As each tube is completed, it moves along the mandrel into the cutting machine that grabs the tube and rotates it as the cutter trims the tube to the correct size. Individual manufacturers have their own processes for cutting, which vary from knives to saws or other methods. The cutting process is completed quickly to avoid leaving burrs or rough edges. The distance determines the length of the mailing tube the cutter moves the tube.
One process of cutting has multiple knives aligned in a row. The distance between the knives and the number of knives is adjusted to fit the desired lengths of the mailing tubes. Multiple tubes can instantly be cut to speed up production.
The first step in the creation of triangular and square mailing tubes is the creation of a design using computer aided design (CAD) software. The program creates a graphic representation of the desired shape of the box and its dimensions. The representations can be generic to fit any type of product or custom made to meet the requirements of a customer's products. In either case, the rendering is examined to produce a digital file for the creation of the die to cut out the box.
The material used to make mailing tubes can be paperboard or corrugated board. The choice of which material to use depends on the use of the mailing tube and the types of treatment it may endure. Corrugated board is considered to be the stronger and more durable of the two types of cardboard.
Paperboard – Paperboard is a standard material used by the packaging industry to manufacture milk cartons, packaging for commercial products, and comes in various grades to fit specific applications. It is made from Kraft paper and test paper with test paper forming the inside layers and Kraft paper the outside layers.
The use of paperboard is limited to mailing tubes that will not face harsh treatment and for packaging items that do not require too much protection. Although it is very sturdy, it does not have the same impact resistance as corrugated boards.
Corrugated Board – Corrugated board is designed to withstand heavy duty use. There are several varieties of corrugated boards, with each type having an outer lining of Kraft paper, a middle lining of wavy fluting, and an inner lining of more Kraft paper or test paper. Corrugated boards are capable of supporting heavy materials. Mailing tubes made using corrugated boards can be used to ship heavy tools, implements, instruments, and other devices. In many cases, corrugated mailing tubes are used to store mailed items due to their sturdy impact resistance. Most corrugated mailing tubes are used multiple times.
A cutting die is used to cut the box from flat sheets of paperboard or corrugated board. The cutting edges of the die are called rules, which are sharpened to cut through the cardboard or slightly dull to score the sheets for flaps, sides, and other folding areas.
Foam on the die holds the cardboard in place to keep it from shifting such that it won’t be torn or scarred. Additionally, the foam part of the die serves as a guide for the rules, so they move straight into the sheet.
In the case of mass production of mailing tubes, multiple dies are mounted around a long cylinder. As large sheets of paperboard or corrugated board pass through, the cylinder rotates and is pressed against the sheets to produce hundreds of mailing tubes rapidly.
Dies come in a wide array of sizes, dimensions, and shapes. Box manufacturers have collections of dies that can be attached to cylinders for manufacturing mailing tubes. The process is efficient, precise, and produces high quality products.
As the boxes leave the die, they are stacked, bound, and prepared to be shipped. They are not folded, which makes it easier to ship them. This process is true for both triangular mailing tubes and square mailing tubes. Hundreds of flat mailing tubes can be palletized using this process.
Like pizza boxes, triangular and square mailing tubes are folded by the customer as they need them. Flattened, the mailing tubes are easier to store and quickly accessible.
Modern technology has produced a wide range of highly creative and innovative boxes designed for displaying products and shipping them. The various types of cardboard mailing tubes are another aspect of this ever growing industrial phenomenon. Manufacturers are continually working to improve the strength and endurance of their products to meet the demands of sensitive and technical products.
Cardboard mailing tubes have become an essential part of product protection. They are made to withstand the rigors of the several million items that are shipped every year. Made of various types of cardboard, mailing tubes make it possible to ship delicate devices and heavy duty tools.
Unlike the large robust boxes designed to package several items, cardboard mailing tubes are small and space saving with a compact design that makes them easy to fill with several items or just one. The size of mailing tubes makes it possible to fit them into limited space when being shipped or stored.
Protection of sensitive and delicate items is one of the main reasons that cardboard mailing tubes are so widely used. The solid rigid wall construction with tightly secured ends makes them ideal for preserving the integrity of shipped items. The design of cardboard mailing tubes limits an item’s movement during shipping, which offers further protection from items being harmed or damaged.
Cardboard mailing tubes have been used for years to send blueprints, maps, designs, and prototypes for customer approval or for governmental projects. The tight seal on cardboard mailing tubes makes them one of the most secure and impenetrable methods for sending priority or confidential documents. Since cardboard mailing tubes seldom burst, their contents become inaccessible to ensure document security and privacy.
Envelopes, folders, and large boxes are an expensive method for shipping documents. They are costly and take up space. Companies have found that shipping documents, prototypes, and plans via cardboard mailing tubes is cost effective and more convenient.
When mail is being sorted and collected, envelopes and folders tend to look like every other piece of mail. They can be thrown in with the regular mail and junk mail without being noticed. This is not possible with cardboard mailing tubes. Their unique shape and appearance differentiate them from the common mail and make them stand out to show their importance.
With all the many benefits of cardboard mailing tubes, it is important that care be taken when selecting a mailing tube to fit the needs of the item to be shipped. Cardboard mailing tube manufacturers have guidelines that they suggest their customers follow when ordering and choosing a cardboard mailing tube. Careful attention during the design and selection process can avoid errors and damage.
The most logical aspect of the selection process is determining the item’s dimensions to be shipped. The mailing tube needs to be large enough to accommodate the size of the item. For accuracy purposes, the length and diameter of an item should be measured. Since most items to be shipped are not round, the diameter will need to be approximated leaving sufficient room for the item to fit into the mailing tube.
Triangular and square mailing tubes may be an alternative to oddly shaped materials since they do not necessitate extraordinary measures for odd shapes.
The selection of the durability of a cardboard mailing tube is dependent on the weight of the item to be shipped. Documents such as maps, plans, blueprints, and posters require a list of resilient mailing tubes compared to instruments and tools. For heavy items, corrugated board mailing tubes are the logical choice while paperboard ones can be used for documents.
Fragile items tend to bend the rules when selecting a cardboard mailing tube since they are lightweight and have little mass but require extreme protection. For these types of materials, paperboard mailing tubes will not provide sufficient protection from impact while corrugated board is designed to endure and withstand concussive forces. Additionally, when selecting a cardboard mailing tube for delicate and fragile items, it is best to choose one with internal padded walls or ones with multiple layers of corrugation.
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