Paper Tubes


Introduction


This article provides comprehensive information about paper tubes, paper core and composite cans. You will learn how these paper and paperboard products are made and their materials of construction as well as paper tube applications, advantages and drawbacks.



Read further to answer questions like:



What‘s the difference between paper tubes, paper tubes and composite cans?


Why should you select paper tube containers instead of plastic, glass, or metal packaging?


What types and sizes of paper tubes are available from leading manufacturers?


How do I specify paper tubes when ordering or submitting an RFQ?


How is the quality of paper tube products I am buying tested and assured?


How easily can I dispose of or recycle used paper tubes and paper cores?


And much more...


Paper Tubes


Paper Tubes from Ace Paper Tube


I. What is a Paper Tube?


Paper tubes consist of paper or paperboard sheet layers wound together to form strong, hollow, and usually cylindrical shapes. The paper layers are laminated or bonded together using adhesives. The wall thickness of the tube can vary depending on the number of layers wrapped during manufacturing.



Paper tubes are also known as paper cores, paperboard tubes, paper cans, fiber drums with paper drum machine, fiber tubes, paper tubing, wound tubes, composite cans, coreboard tubes, and cardboard tubes. While widely used everywhere, the term "cardboard tube" is a misnomer. Cardboard consists of three kraft layers with the central layer corrugated.


II. Paper Tube Types and Shapes


Paper Tube and Core Types


While paper tubes, paper cores and related products are all made from wound plies of paper or paperboard. Paper tubes with paper tube cutting machine or cores can be constructed from one, two or many plies of brown kraft paper or paperboard.



The innermost layer or ply, the liner, and the outermost layer, the wrap, can consist of different materials (foil, film, etc.) or specialized paper. The specialized paper and materials can provide water resistance, graphics or labeling, or a specific color.


The two main types of paper tubes and cores include spiral wound and convolute or parallel wound paper tubes. Convolute wound tubes are used in applications requiring high bend strength, crush resistance and dynamic strength.



A spiral wound tube has the paper ply or plies wrapped around at an angle to the tube's axis. In convolute tubes, the outer two edges of the paper strip are wrapped parallel or at a 90-degree angle to the tube‘s axis.


Paper tubes have thinner walls and are widely used as containers or packaging for products with paper packaging machine.


A paper core is essentially a heavy-walled paper tube. The much thicker wall of paper cores enables their use in winding webs or sheets of flexible material into rolls in converting operations.


Paper machines produce extremely large rolls (also known as machine, jumbo, tambour or mother rolls), which are rotary slit or converted into many narrower smaller rolls on a winder with a paperboard core. Similar jumbo rolls are converted in plastic film, foil, textile and coated abrasive plants.



You will be surprised that not all paper tubes are geared toward packaging applications. Paper cores can be machine elements. Paper cores used for winding large rolls in a paper mill or plastic film production plant are machine elements and require extremely high strength paper cores, which are often convoluted.


Paper cores for retail or small diameter width rolls of adhesive tape, label, foil, paper, tissue or plastic film are a packaging and dispensing product, which can consist of a thinner, spiral wound core.


The paper tube material is rotary or saw cut into paper cans or composite cans, shipping tubes, push tubes, pyrotechnic tubes, display poles, converting cores, concrete piling forms, and other paper tube products.



Large fiber or composite drums and even paper straws are manufactured in a similar winding process. Convolute winders are typically used to make composite drums, which are a more eco-friendly alternative to steel drums. Paper straws are spiral wound at very high speeds.



Paper Tube Shapes


You will find that most paper tubes have a cylindrical shape or round cross-section, but paper tubes can be made with square, oval, hexagonal, triangular, and other custom shapes by using a square, oval and custom shaped winding mandrel. Custom shapes are useful for fitting the tube specifically to a part or product shape while eliminating wasted space and additional spacers or packing material.



Tapered paper tubes or paper cones are wound with a cone-shaped mandrel. Paper cones are used as yarn carriers in the textile industry.



For certain applications, you may want your paper tubes slit or cut along their length to make half-shells such as facilitates covering large rolls for protection. They can be reconnected with tape or h-profiles. You will find covering a paper roll or coiled steel roll easier with half-shells compared to sliding a roll into a large protective paper tube.


III. How Are Paper Tubes Made?


Paper Tube and Core Manufacturing


Paper tube and core manufacturing is a paper converting process combining web slitting, web winding and lamination or adhesive bonding steps. Through multiple wraps or revolutions of one or more paper webs or ribbons around a steel mandrel, several layers or plies of paper or paperboard are laminated together around a steel mandrel to form rigid, high strength tubes or fiber cores with paper core making machine.



In my experience, plies are usually around 2 to 10 inches (50 to 250 mm) wide, but in some plies are as wide as 20 inches (500 mm). Ply thicknesses are typically around 0.008 to 0.050 (0.2 to 1.3 mm). The number of plies ranges from 1 to 50 or more, but paper cores with 3 to 30 plies are more common.


We find that the strength of paper core is a function of the paperboard ply bond strength, ply thickness, bond area or overlap and adhesive bond strength. What I find interesting is that paperboards are made in a single thicker papermaking process or by bonding or laminating several plies together, so some paper tubes can consist of laminations or laminated plies!



To me, a review of related patents and technology definitions in the USPTO website can help provide a greater understanding and in-depth details on the paper tube making process. Subclass B31C provides the United States Patent and Trademark Office (USPTO) cooperative patent classification (CPC) and technology definitions for paper or wound tube manufacturing processes. B31C 9/00 is defined as "Simultaneous forming of cylindrical and conical shapes by winding separate webs, e.g. forming bottles".


The paper tube making process can include winding, folding and bending depending on the specific shape (round, square, conical, etc.) desired in the finished end product.



Spiral Paper Tube or Core Manufacturing


In the spiral paper tube or core manufacturing process with paper core machine, jumbo rolls of paper, paperboard, and lining materials are converted in a rotary slitting operation with paper slitting machine into narrower width ribbons. The paper ribbons are rewound into narrow rolls on rewinding stands.



The narrow paper ribbon rolls are stacked in what looks to me like giant stacks of "poker chips". The "poker chip" stacks or rolls of paper ribbon are transported and loaded into the tube manufacturing machine.



Narrow paper webs or ribbons from several different rolls are passed through guides and attached, adhered or taped to a steel mandrel in an overlapping fashion or with spacing between leading edges of the paper ribbons. The festooning or spacing allows the ribbons to feed without interference between ribbons.



You will see that by attaching the leading edge or end of the ribbon obliquely or at an angle less than 90 degrees to the axis of the mandrel, the result is the formation of spiral during winding.



The outer diameter of the steel mandrel determines the inner diameter of the finished paper tube. The wall thickness of the tube is a function of the thickness of the paper or paperboard ribbons, the adhesive thickness and the number of ribbons used in the process.



Adhesive or glue is applied to each paper ribbon or ply before being wound onto the steel mandrel. In my experience coating webs of paper, cloth, vulcanized fibre and plastic film, a variety of web coaters can apply the adhesive to the plies such as:



Roll coaters


Reverse roll coaters


Slot die coaters


Extrusion coaters


Curtain coaters


Brush coaters


Spray coaters


Blade coaters


Metering bar coaters


Dip coaters


What‘s fascinating is how the paper tube belt twists around in a helical shape to continuously form and bond the paper tube plies together. The flexible belt wraps around and applies pressure to the paper layers, which assures the proper formation of adhesive bonds between the paper ribbons. The fabric reinforced rubber belt also advances the tube forward along the mandrel.



I have to imagine that the stresses and performance requirements on the paper tube forming belt are enormous. These belts are endless or seamless and prevent marking. They have high tensile strength and high friction to grab and move the tube along and easy to clean. Nitta, Passaic, Rainbow are some of the suppliers of tube forming belts.



Next, we see that as additional paper plies are added at one end of the paper tube forming mandrel, the formed or laminated paper tube slides off the other end of the mandrel and is cut to length using rotary blade slicing or offline sawing operations. Additional deburring of the tube end edge may be performed depending on the end-use.



Another interesting aspect of the paper tube manufacturing process to me is the ability to make an enormous amount of highly customized paper tube product or materials combinations by using different material plies.




Liner or lining layers are used on the inner diameter (first ribbon) or outer diameter (last ribbon) of the tube to improve water resistance, moisture resistance or grease resistance. Liners can consist of metal sheet, foil, coated paper (wax, silicone, or plastic), plastic film and other protective materials.


If your current application is not satisfied with existing paper tubes, you can well imagine a custom paper tube manufacturer can engineer a new combination of liners, plies and wraps to meet the needs of your specialized application. As long as the order volume is sufficient.


One great ability I find in paper tube manufacturing is the ability to provide branding through labeling or print to enhance marketing inside and out. If printed or decorative graphics are required on the inside or outside of the paper tube, then the printed paper ribbons or ribbons made of printable material can be used on the first and last ribbons. A white paper or paperboard could be used on the outer layer with stronger brown kraft paper used on the inner layers.


Convolute Paper Tube or Core Manufacturing


In the parallel or convolute paper tube or core manufacturing process, jumbo rolls of paper, paperboard, and lining materials are converted in a slitting operation, but not into the very narrow width ribbons used in spiral tube manufacturing. In the convolute paper tube or core manufacturing process, the leading edge of the ribbon is parallel to the axis of the paper tube mandrel, so a single seam or flap along the length of the paper tube results.



An external metal roll can apply pressure instead of a belt, which squeezes out any voids or air pockets providing better contact of the adhesive and therefore a stronger adhesive bond between paper plies. Since the paper web is wider, higher pressures and tension can be applied in the convolute winding process. The higher pressures and tensions in convolute paper tube manufacturing result in tubes with higher strength compared to the spiral wound tubes.