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...
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, 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 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.
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.
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, jumbo rolls of paper, paperboard, and lining materials are converted in a rotary slitting operation 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.
Convolute paper cores have higher beam strength compared to spiral wound cores, which makes convolute cores desirable in web manufacturing and converting. Convolute paper tubes processes are used to form high strength, heavy-duty cores for winding and unwinding of large jumbo rolls of flexible webs such as:
- Paper and paper board
- Coated abrasives
- Plastic films and rubber sheet
- Woven and nonwoven textiles
- Metal sheet and foil
- Carpeting and flooring
When we think about a paper core, we need to think of them like other rotating components such as bearings, gears, chucks, and shafts. In heavy-duty converting operations, paper cores are considered a machine part. They are not a packaging product because they impact the function and integrity of web manufacturing and handling machines. Spiral wound paper cores are sufficient for lighter duty applications such as packaging and dispensing smaller width and diameter rolls of labels, tape, foil, tissue paper, paper, or plastic film.
Combined Convolute and Spiral Tube Manufacturing
The spiral and convolute tube manufacturing processes are combined to produce some tubes. For instance, a spiral wound tube made of kraft paper could have an outer white paper or plastic layer with graphics and labeling wound around the outside of the tube using a convolute winding process.
Related and Patented Paper Tube Manufacturing Processes
You use paper cores and related products every day in your daily life without ever recognizing it. Paper towels, tissue, aluminum foil, plastic wrap are all wound on a paper tube for easy dispensing. If you open up your kitchen cabinet, you will see a wide variety of paper canisters, composite cans, and other paper tube containers. Fiber drums, straw making, and paper cups are made using similar technology.
Fiber drum machines, straw making machines, paper cup machines and composite can machines use process technology similar to paper tube winders.
Also, paper tube manufacturers and machinery OEMs have patented and proprietary paper tube manufacturing processes. These specialized processes are used to form tubes and cores with higher strength, lower weight or other unique properties and functions. For example, PAKEA has designed and patented the SIRPAK® linear tube forming systemto enhance the production of non-round-shaped composite cans.
Paper Tube Cutting and Recutting
After a paper tube is formed on a spiral or convolute winder, the tubes are cut into short lengths on in-line and offline cutters. Spiral tube material is continuously produced as the laminated spiral tube slides off the mandrel. The spiral tube material might be cut to the finished length with an inline cutter or into a longer piece, which is then fed to an offline recutter or recutting machine. The intermediate length might have an outer wrap of protective film or foil, printed graphics and labeling or a surface treatment applied before recutting to the finished length. Inline cutting is done using rotary blade cutting.
If you need a very clean cut and consistent lengths, then rotary blade cut tubes are for you. Rotary cutting blades or saw cutting is employed for offline cutting. Rotary cutting tends to produce a cleaner, sharper edge as well as tighter tolerances. Saw cutting might be useful on very thick-walled tubes, but the burrs and dust generated need to be removed from the paper tube or core. Tighter cut-to-length tolerances can be held using blade cutting. Saw cuts paper tube or core lengths can vary as much as 1/16” (0.062”).
Tube Finishing Operations
We saw above how the varied permutations of ply materials can create multitudes of paper tube product possibilities. Even more paper tube variations are possible through surface treatments, coatings, dips, impregnations and offline convolute wraps.
Paper tube surface treatments can include dipping into or impregnating with wax, silicone or other waterproofing coatings to increase the water-resistance of the paper tube.
For certain winding applications, the inner or outer diameters of the tube are polished and burrs on the outer edges are removed so the paper core can be loaded onto machinery and move freely.
Printing of graphics and applying labeling wraps onto the tube for packaging uses can be performed in an inline or offline operation. Both convolute and spiral wrapping processes are used to apply to labels.
Tube End Forming, Cutting and Capping
If the paper tube product is to be used as a spacer, concrete form, mask or pole, then the cut-to-length paper tube might be complete and ready to package and ship to a customer. If the paper tube is for packaging, then additional slotting, die-cutting, flanging, sealing, capping, end rolling, or end forming are required to produce a shipping tube, paper canister or composite can.
You will also appreciate the value-added secondary operations such as embossing, notching, slotting, slitting, and die-cutting windows. Paper cores may have notches cut into the ends of the tubes to facilitate winding and unwinding of converted film, tape, cloth or other roll stock materials.
Openings can be cut into the side of a paper tube container and then a plastic film applied on the inner diameter to provide a window for viewing the packaged goods inside. Embossing provides a raised pattern on the surface. Functional embossing or raised bumps on the surface of a paper core can allow web materials to better grip the core surface during winding.
A closure feature is added onto a paper tube to produce a paper can, mailing tube, or other tubular composite packaging material. Paper tube closures can be made by rolling or forming the end of the tube for creating rounded edges and inserting a paper disc, by inserting a plug or cap, and by combination for end forming and capping.
The closure on the end of a paper tube can be permanent or removable. Permanently closed ends include:
- Paper cup ends
- Fixed plastic plug ends or caps
- Seamed metal ends, plug ends or caps
Paper tube containers can also have an open metal seamed end, which accepts a removable metal friction plug.
A paper tube closure type, which is very compelling to me due to its simplicity and ease of function, is a snap-loc closure. Tucked, crimped or snap-loc end closures are one of the easiest to make and use closing options. Crimped end closures are also known as EZ open crimp, “snap-seal” or “self-seal” ends. Two edges of the paper tube ends are bent inward. The snap-loc flaps can be pinched open and popped closed by an end-user.
Tubes can also be star crimped and used as plugs inside the end of cores to provide additional support and prevent the core end from collapse or crushing. Star crimped paper tubing has crimps parallel to the paper tube’s axis. Similar crimping is widely used on round metal ducting to assemble ductwork.
Storage, shipping and mailing tubes typically have plastic, wood or metal plugs inserted inside the tube ends to provide closure. While the friction fit plugs may have a tight or snug fit, some applications require additional tape or stapling through the tube wall to avoid dislodgement of the plug and unwanted opening during shipping or handling.
Another option is two caps, which fit over the outside of the tube ends. Caps can be made of plastic, metal or paper. Specialized plugs and caps are available for specific end uses. Slotted caps facilitate coin or ticket collection. Sifter caps with perforation allow dispensing of powders and dry goods. Plugs or caps with a square exterior portion or tab can provide an anti-roll feature.
Paper tube containers can be constructed using telescoping paper tubes or two paper tubes with the inner paper tube having an outer diameter slightly less than the inner diameter of the outer paper tube. Two-piece and three-piece telescopic paper tube containers are usually made with rolled ends with paper or wooden disc plugs.
- Two-piece telescopic tubes can be adjustable in length allowing different length documents or goods to be packaged or stored with one paper tube product.
- Three-piece paper tube containers are often used for packaging wine, cosmetics and other high-end commodities.
While you probably think a paper tube-based product is only suitable for dry goods, surprisingly - I have found that this is not the case. In packaging applications of a wet or frozen product such as frozen orange juice, flanging, sealing and capping of the paper tube is required to create a sealed, leak-proof package. Typically, “tin end” or metal seamed ends are used where a flange is created in the end of the tube and metal cap with additional sealant inside the joint.
Paper Tube Palletizing and Packaging
I have found that the final step in manufacturing any product, the packaging step, is often overlooked in attention. The packaging is important because damage can destroy a lot of hard work if the product is not protected during transport as well as in storage at the customer site.
The final step before finished paper tubes, paper cores and other paper tube products can be shipped to customers is palletizing and packaging to assure the tubes are not damaged during transport. Paper tubes and cores can be packaged in a variety of ways depending on the customer requirements. They are often packed into:
- Corrugated cartons
- Returnable steel carts with wheels, which provides high mobility at a customer’s plant.
Also, some paper tube manufacturers provide filling and sealing services or packaging of their customers’ products in paper tube containers.
Paper Tube Materials of Construction
You will find that the majority of paper tubes and paper cores are constructed from kraft paper and paperboard. Paper and paperboard are both derived from pulp, cellulose or plant fibers. Paperboard is generally 12 points or 0.012 inches or thicker, while paper is less than 12 points according to TAPPI definitions. ISO standards define paperboard as a paper with a grammage above 250 g/m2.
Kraft paper is the type of paper most widely used to make paper tubes due to its strength. Kraft paper is made from softwood pulp with long fibers and is stronger than white or stationary type paper. In fact, the term “kraft” is derived from a German and Swedish word for strength.
Coreboard paper is a type of paperboard made for manufacturing paper cores. Coreboard paper is typically made from 100% recycled material. Uncoated recycled paperboard (URB) is also used to make paper tubes and cores.
Paper tube consist of one to many plies consisting of three types:
- Liner or ID Ply – The liner ply is on the inner diameter and it is the first ply wrapped around the mandrel during spiral tube winding. If a liner is used, then there is only one.
- Intermediate Plies – Intermediate plies lie between the liner and wrap. Paper tubes can have many intermediate plies.
- Warp or OD Ply –The liner ply is on the outer diameter and it is the last ply wrapped around the mandrel during spiral tube winding. If a wrap is used, then there is only one.
Paper cores can be made with just kraft paper or paperboard in every ply or with different materials for the liner and wrap. For instance, the liner could consist of metal foil to provide a moisture barrier, the intermediate plie made of kraft paper for strength and then the wrap of white paper for printed labeling. A wide range of material combinations are possible in the liner, intermediate and wrap layers.
Liner and wrap materials can include:
- Color glazed papers
- Foil labels
- Glassine or wax paper
- Paper with printed labeling and graphics
- Plain kraft paper
- Plain paperboard
- Plastic (polyester, polyethylene, polypropylene) laminated to kraft
- Plastic laminated foil
- Silicone Coated paper
- Vinyl laminated foil
- White, brown, metallic, color or black kraft paper
By taking advantage of the ability to include unique non-paper layers during paper tube manufacturing, you will find that some very interesting and high-performance materials can be made.
For electrical insulation, waterproofing, thermal insulation, mechanical strength, and other properties for specialized applications, paper tubes can be manufactured from webs of non-paper materials.
The engineered materials can be wound in addition to or in place of conventional pulp or cellulose-based paper webs to provide specialized characteristics for specific applications. For example, specialized tubes can include:
- Food grade paper tubes are made using protective foil and plastic film liners and wraps, which provide a high degree of water resistance.
- Electrical grade paper tubes are constructed using plies of electrically insulating paper, dielectric kraft, fishpaper, aramid, E-glass fibers, inorganic fibers, and other dielectric materials.
- Corrosion or rust-inhibiting grade or VCI paper tube has a liner of vapor phase corrosion inhibition (VCI) paper, which releases a volatile into the container or paper tube protecting against rust and corrosion in damp environments. A VCI lined paper tube will protect steel rods, steel bars, steel angle, steel channel, gun barrel, steel shaft, and other steel stock and fabricated steel shapes from corrosion.
Specialty ply materials include:
- Aramid (Nomex or Kevlar)
- Dielectric crepe paper
- Dielectric Kraft paper
- Glass or inorganic fiber based paper (CeQUIN® or ParaQUIN ENV)
- Leather-like materials
- Mica paper tubes
- Phenolic impregnated kraft
- Textured materials
- VCI or rust inhibiting paper
- Vulcanized fiber or fishpaper
- Woven cloth or textiles
Typically, the adhesives are based on water-based polymers, polyvinyl alcohol, dextrin, and hot melt polymers. Some paper tube adhesives are modified with clay or other fillers. If specialty non-cellulose papers or nonwovens are used in paper tube construction, then the specialty adhesive or thermoset resins will likely be required to bond the plies. Paper tubes can be impregnated with wax, resins, silicone or other polymers to increase water resistance or alter mechanical and electrical properties.
IV. How are Paper Tubes Specified and Ordered?
Paper Tube Size Specifications
Paper tubes are measured and specified according to their inner diameter (ID), wall thickness and length. For packaging or containing type applications, the ID and length should be based on the dimensions of the product being packed.
The product being packed should fit snug in the tube to avoid any movement during shipping. Still, enough clearance between the product and tube ID should be provided so the product slides in easily.
If a product is a powder or granular, chemical, or grease, then the volume desired per paper tube canister will determine the dimensions required. The outer diameter is less of a concern for a mailing tube or any paper tube canister.
Here’s the bottom line, the wall thickness of the paper tube will impact the flat crush resistance of the paper tube. The wall thickness of the paper tube will impact the flat crush resistance of the paper tube. The wall thickness should be sufficient to avoid crushing during shipping, handling and storage while avoiding excessive thickness, which would increase cost and somewhat negate the light-weight advantage of using a paper tube.
Paper cores for heavy converting typically require heavier walls to withstand the stresses developed during winding. The specific wall thickness will depend on the width and diameter of the web materials being wound up.
A narrow adhesive tape roll for retail packaging can use a thinner wall compared to a paper core for winding a large roll of tape, film, paper, or cloth converted from a jumbo or mother roll.
The dimensions of concrete form or piling tubes will depend on the desired diameter of the concrete piling or support. Large ID diameter paper tubes are typically specified for the concrete form or piling tubes.
Dimensional tolerances are an additional consideration. Tight tolerances should not be specified unless there is a real requirement in the application. Over-specifying tolerances can needlessly increase costs. The best part is paper tubes and cores are built upon a steel mandrel, which gives excellent tolerance control of the tube ID.
Also, paper tubes and cores can absorb and release moisture over time causing shrinkage or expansion or a change in the paper tube’s dimensions. Dimensional stability is a function of the paper tube’s resistance to moisture absorption or release (drying out).
Blade cut tubes can hold much tighter tolerances compared to saw cut tubes, which might be a consideration if the paper tube is used for spacing, masking or protection of threads, shafts, spindles, and other mechanical components. Note the difference between smooth blade cut edges and rough saw cut edges in the image.
Some knowledge of the capabilities of paper tube manufacturers can assist in understanding what sizes are available and feasible. The table above provides a review of the paper tube manufacturing capabilities of several leading paper tube and core manufacturers. Summarizing the dimensional manufacturing capability of this group of leading paper tube and core suppliers:
- The smallest ID paper tube or core size available is ¼ inch (0.25 inch)
- The largest ID paper tube size or core available is 30 inches (2 ½ feet)
- The smallest wall thickness paper tube or core size available is 0.018 inches.
- The largest wall thickness paper tube or core size available is 0.75 inches.
- The shortest paper tube or core size available is ¼ inch (0.25 inch)
- The longest paper tube or core size available is 350 inches (approximately 29 feet)
While the table indicates size range capabilities available, a manufacturer needs to be contacted to determine if the dimensions of the specific paper tube you require can be produced on their winders and cutters. For instance, a paper tube product with a 0.25 ID, 0.75 wall thickness and a 0.375 length might not be feasible.
Even if your project is outside a manufacturer’s capabilities, new tooling or machinery can be purchased and amortized for a high-volume project with sufficient annual order quantities. Paper tube tooling tends to be less expensive compared to tooling used in other manufacturing processes like injection molding or extrusion.
When ordering a paper tube, paper core or other paper tube products, the end-use or application is important to discuss with the paper tube manufacturer because their engineers and experts can recommend the appropriate materials of construction and strength required (flat crush, radial crush, dynamic, burst) as well as any additional features or paper tube modification required to meet the demand of your application.
For example, paper concrete form tubes have to withstand the weight of the liquid concrete. If you are pouring a longer depth, then the wall thickness and strength must be sufficient to withstand the pressure.
Typically, commercial-grade form tubes can handle pours of up to 20 feet in depth. Contractor grade type form tubes can only handle pours of 12 feet. Concrete form tubes are available in diameters as large as 60 inches, but the most common sizes include 6, 8, 12, 15, 16, 18, 20, 24 and 36 inches.
Paper cores for converting or winding web materials are typically available with inside diameters of 3 or 6 inches with varying performance or strength levels. The higher strength or grade cores can be used on larger finished roll sizes, heavier weight rolls and at higher winding or unwinding speeds.
The table below shows the Graphic Communications Association (GCA) and the Composite Can and Tube Institute (CCTI) paper core grades. The table provides the minimum test performance requirements for each grade. CCTI provides Automated Paper Mill Core guidelines (as an Excel spreadsheet), to calculate a recommended core grade for your application.
In addition, a paper tube or core inquiry or request for quote (RFQ) should include an estimate of the number of paper tubes or cores required and how often they will be reordered. Many custom paper tube manufacturers have minimum order quantities.
V. Paper Tube Properties and Testing
Moisture adsorption and water resistance can be important properties for many applications. Cobb testing is typically used to measure the moisture absorption properties of paper. A paper tube’s dimensional stability due to the resistance to moisture absorption or release (drying out) is another important property.
Shrinkage or swelling can cause paper products to warp or distort, which would be troublesome in paper core applications where the material is being wound up. A bent, warped or out-of-round tube would generate wrinkles and other defects in a web material such as adhesive tape, paper, plastic film or foil.
A TAPPI survey indicated 50% of the web breaks in paper mills were the result of roll or core defects. A large run of material could quickly turn into waste if the paper core straightness, roundness, and strength are not within the specifications required for the application.
Smoothness and the grooves from the spiral winding process can create wrinkles during web winding. External burrs from saw cutting could also generate a wrinkle. To reduce wrinkles, you might want to request that your outer paper core surfaces are skived and polished to increase smoothness.
- Smoothness can impact how easily a small converting core rotates on a spindle during dispensing.
- Burrs on internal tube edges can also be a factor in loading a core onto a machine. Burrs can catch on plugs or core chucks making insertion difficult. Smoothness and burrs can be determined by visual inspection, touch and surface profilometry.
A low-quality paper core can result in web breaks and exploding rolls, which can cause a paper mill or plastic film plant thousands of dollars and possibly damage equipment and harm workers. Several different mechanical tests are used to measure the strength and suitability of paper tubes and core for specific applications including flat or side-to-side crush, radial crush, flexural or bend, ring, and dynamic load testing.
Flexural Stiffness - CCTI T-150 - The industrial test methods in this standard are divided into two parts. Part one determines the flexural modulus and Bending Stiffness of a paper using modal analysis and three-point bending testing procedures. Part two provides a method for calculating the theoretical critical speed of paper cores used on printing presses and high-speed web converting machinery.
Tests for performance under bending stresses and roll vibrations during winding and unwinding of web materials. Flexural stiffness is also a predictor for resistance to core explosions. Flexural strength or bend strength tests measure the resistance to a paper core sagging under an applied load to the center of a length. Sagging or distorted cores can cause vibration and misshapen rolls.
CCTI-108 Flat Crush Side-to-Side Crush Test - Tests for crushing performance of a paper tube or core during handling and transportation of a roll wound around a paper core. Flat crush strength tests push two flat plates or anvils against the outer walls of a tube to measure the crush strength. Flat crush strength is useful for paper tubes and composite cans for packaging applications.
CCTI-148 Radial Crush Test - For paper cores, the radial crush test better simulates the load conditions during winding.
CCTI T-149 Dynamic Load Test – Tests for performance under cylindrical loading during winding and unwinding in paper mills, plastic film plants and other web making facilities. Dynamic strength testing measures the maximum roll weight a core can support between core chucks in terms of lifetime or number of revolutions.
In my experience, I have found that materials often fail at lower stresses or loads when cyclic loading conditions versus static loads. Dynamic load or dynamic strength testing simulates the effect of cyclic loads generated by tension and the high-speed revolutions of the roll during winding.
CCTI T-156 Static Chuck Chew-Out Resistance - Large rolls of paper, film and other materials generate an enormous amount of momentum during winding. When rolls are accelerated or braked the torque is transferred to the core through the core chucks and the tension of the web, which eventually results in core chewout or tearing apart of inner diameter of the core by the chuck. I believe that chewout is an area requiring improved test methods.
Two standards organizations, International Standards Organization (ISO) and Composite Can and Tube Institute (CCTI), provide test methods for flat crush testing: ISO 11093-6:2005 Paper and board — Testing of cores — Part 6: Determination of bending strength by the three-point method and Core Compression (Side-to-Side Flat Crush, CCTI T108). Composite Can and Tube Institute (CCTI) provides standards on measuring the dimensions of composite cans, tubes and core. CCTI also has standards for dimensional stability, water vapor permeability (moisture resistance), and warpage measurement.
The Technical Association of Pulp and Paper Industries (TAPPI) provides standards for the paper raw materials such as paper and paperboard used to manufacture paper tubes, paper cores, paper discs, paper caps, paper end caps and paper spools.
VI. How Are Paper Tubes Used?
Paper Tube End-uses and Applications
A wide variety of industries consume paper tubes to meet several different end use functions including:
- Containing & Packaging
- Forming & Construction
- Insulating & Dampening
- Supporting & Holding
- Winding & Carrying
Containing and Packaging
Containing and packaging is probably the largest application segment for paper tubes. Mailing or shipping tubes are used to package large documents with folding such as maps, posters, prints of artwork, original paintings, blueprints or engineering drawings and architectural plans.
Powder tubes are designed to contain dry goods and granulated materials. Powder tubes often have rotary shaker or sifter tops to facilitate dispensing such as disposable salt and pepper shakers.
Frozen lemonade and cookie dough are packaged in food-grade paper tube cans,which have liners and sealed ends to safely contain the food product. Telescopic tubes are often used to package wine bottles, perfume and cosmetics.
Push-up tubes with oil-resistant liners can be used to dispense lip balms, lubricating grease, caulks, adhesives, deodorant and repair compounds.
Chemicals, active pharmaceutical ingredients, pesticides and fertilizers can be packaged in paper tube cans and composite drums by first lining the container with a plastic bag.
Forming & Construction
Another application that I personally find interesting is the use of paper tubes in construction. Large diameter spiral wound paper tubes are to form concrete pilings. The concrete is poured into the tube, which may contain rebar and remesh. Paper dowel sleeves are smaller diameter paper tubes used to create voids or channels within cast concrete for running communication cables, electrical wiring and plumbing. Some architects have experimented with the use of paper tubes as framing materials for emergency or temporary shelters.
Insulating and Dampening
Paper tubes have a natural ability to dampen vibration due to the fibrous structure of paperboard. Paper tubes have better thermal insulating properties compared to metal tubing.
Specialized dielectric crepe or kraft papers can be used to produce electrically insulating or dielectric paper tubes. Engineered paper and saturation with engineered filled resins can provide thermal conductivity or thermal insulation.
Protecting and Masking
Paper tubes are used to protect spindles, bolt threads, polished shafts, spindles, end mill teeth, plug gages, drill bits and other mechanical components. A protective tube on a spindle or bolt threads prevents impacts with other metal components from nicking or distorting the threads.
Paper tube masks are slid over threads or shafts to allow the selective application of coatings or adhesives without the coating of the masked area.
Spacing and Supporting
Paper tubes act as display poles to support signs in stores and exhibits. Paper tube spacers are used within other packages to prevent movement and protect products from damage. For instance, paper tube spacers are used to properly position and protect automotive wheel hubs during shipment. Paper tube spacers also find application as reinforcing corner posts and supports within some packages.
Winding / Carrying
Paper cores, paper cones and paper spools are widely applied in the winding, carrying and dispensing of wires, cable, tubing, foils, yarn, rope and other webs or forms of roll stock. The Paper spool consists of a paper core with two chipboard paper flanges. The agricultural industry even uses paper core to roll up sod.
VII. Paper Tube and Core Advantages and Drawbacks
Paper tubes and cores have several advantages compared to plastic or metal tubes:
Low cost – Paper is much lower in cost compared to plastic, glass and metal
Lightweight – Paper tubes consist of lightweight material with lower density than most other packaging materials. Unbleached kraft paper has a density of 36 to 43 lb/ft3 (0.58 to 0.69 g/cm3) whereas aluminum, the lightest metal used in packaging, has a density of 168 lb/ft3 (2.7 g/cm3), soda lime bottling glass has a density of 157 lb/ft3 (2.5 g/cm3), common packaging plastics (PE, PP and PET) have densities ranging from 56 to 87 lb/ft3 (0.9 to 1.4 g/cm3).
Tough & Impact Resistant – Paper tubes are tough and impact resistant compared to packaging material like glass and some plastics. Paper tube containers are used to protect wine and other bottles from impacts.
Easier to Print – Paper is easier to print graphics and labeling on compared to glass, plastic or metal, which might require special coatings, treatments or a paper label.
Light Blocking – Paper tube container are opaque or non-transparent and can block sunlight to protect light-sensitive foods, wines, beverage, drugs and other light-sensitive goods.
Sustainable & Ecofriendly – Paper tubes are made from up to 100% recycled paper products and they can be recycled.
Proven & Evolving Technology - Well-established manufacturing processes, standards and practices are used to control paper tube and core manufacturing technology. The paper and converting industries are constantly evolving, developing new technologies, more efficient methods to reduce energy consumption and waste.
Paper tube and cores have drawbacks compared to similar products made from metals, plastic or glass:
- Not Waterproof – Unlike plastics, glass and metals paper tubes can absorb water and moisture in damp environments.
- Dimensional Stability – The absorption of moisture or release of moisture can cause dimensional changes and distortion or warping.
- Lower Strength – Paper tubes and cores are not as strong as high strength metal, fiberglass or engineered plastics.
- Dust / Tearing – Cutting edges can generate dust. Paper can fray or tear over time.
- Chew-out - Core ends can experience “chew-out” after extended use and high loads.
- Non-transparent – Customers cannot see through the paper tube container and view the product unless a window is added to the container.
VIII. Recycling and Sustainability
Industries are increasingly switching to eco-friendly and sustainable packaging and component products such as paper tubes to reduce their carbon footprint and portray a better image to their customers. Many consumers prefer eco-friendly packaging, and it can impact their purchasing choices.
We can all see the marketing and consumer acceptance and cost advantages of paper tubes in packaging and product selection. The best part? A paper tube product can also reduce the costs involved in dealing with environmental regulations of plastic and metal goods. Volatile organic compounds (VOCs) and heavy metals are regulated.
Customers purchasing paper tube products should have to be as concerned with compliance to:
- Notices under US California Proposition 65.
- EU REACH regulations.
- Heavy metal limits of the US Model Toxics in Packaging rules.
- Article 11 of EU Directive 94/62/EC.
Paper tube and core manufacturing is a very eco-friendly and sustainable process for several reasons:
- Sustainable & Renewable Raw Materials – paper and paperboard are derived from wood, cellulose and plant-based, which can be sustainably harvested and replanted.
- Waste & Customer Waste Recycling - Scrap from manufacturing and discarded paper cores, paper tubes, paper, and paperboard are sent back to paper mills and recycled, which reduces virgin pulp consumption.
Collection and Reuse Programs - Many paper tube manufacturers have a paper tube and core collection and re-use programs to facilitate the gathering of used cores from their customers as well as paper and paperboard scrap from their communities.
- 100% Recycled - Many paper tube and core manufacturers use 100% recycled material, which was made from discarded paper cores, paper tubes, paper, and paperboard.
- Reduction of Greenhouse Gases – When paper tube packaging replaces plastic and metal packaging, fewer greenhouse gases should be released into the atmosphere. While paper processing produces some greenhouse gases, metal and plastic production generates far more. In addition, the growth of trees and forestry management helps to capture greenhouse gases.
- Biodegradability – Paper tubes and cores are biodegradable, so any scrap or used tubes that bypass recycling and make their way into a landfill will decompose without harm to the environment.
Natural / Eco-safe Material – Paper tubes and cores are made from natural plant materials and are ecologically safe because they do not contain any toxic chemicals or heavy metals. Paper tubes buried in the earth will compost in 1 to 2 months and add nutrients back into the soil.
- ID, wall thickness and length are the key specifications when specifying and ordering a paper tube and paper cores.
- Today’s paper tube manufacturers produce a vast range of product variations using time-tested methods, which are constantly upgraded with new technology innovations.
- Paper tube manufacturing experts know how to select the specific material combinations, diameters, lengths, finishes, and end closures for a broad range of industry applications.
- Paper tube manufacturing experts are willing to work with customers on the development of new applications that would benefit from paper tube technology.
- The outlook for increased use of paper tubes and cores is extremely promising considering the broad range of capabilities that modern paper tube and core manufacturers can provide to their customers as well as the benefits to the environment.