This article takes an in depth look at Tube Fabricating Machinery.
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Tube fabricating machinery refers to equipment used to permanently bend, cut, or shape tubes and pipes into various configurations. These machines typically handle tubes made from ductile and malleable materials such as stainless steel, aluminum, bronze, brass, and titanium. Most techniques used in tube forming involve metal coldworking processes.
Different types of machinery are employed to transform blank straight tubes into more functional forms. Each machine alters the geometry of a straight tube in its own way, usually by deforming the material. Formed tubes have numerous applications, many of which will be discussed in subsequent chapters.
Tube bending is a vital metalworking process essential for shaping tubes and pipes to precise specifications required in manufacturing and industrial applications. During the tube bending process, the tube undergoes controlled deformation, experiencing a combination of tensile and compressive forces. The outer arc of the bend is stretched and elongated by tensile stress, while the inner arc is thickened under compression. This plastic deformation is carefully managed to maintain tube integrity, avoid defects, and meet quality standards for dimensional accuracy and repeatability.
The applications for tube bending machinery are diverse, spanning across industries such as automotive manufacturing, aerospace, HVAC (heating, ventilation, and air conditioning), shipbuilding, furniture fabrication, and even musical instrument production. In piping systems, bent tubes are integral for creating pipe elbows and changes in direction to facilitate efficient fluid flow management. Precision tube bending is also critical in constructing structural frameworks, exhaust systems, heat exchangers, and roll cages.
Various tube bending methods and machinery types are designed to address specific engineering requirements, material properties, tube diameters, and wall thicknesses. The two major categories of tube bending include:
Modern tube benders are available in manual, semi-automatic, and computer numerically controlled (CNC) tube bending machines, with CNC tube benders offering high-speed automation, accuracy, and programmable control ideal for complex or high-volume tube fabrication.
Rotary draw benders are advanced tube bending machines widely utilized in CNC tube bending and automated tube fabrication. These bending systems use interlocking dies, including bend dies, clamp dies, pressure dies, and wiper dies to safeguard the tube against collapsing, wrinkling, ovality, and excessive wall thinning. The precise tooling design ensures consistent results when bending steel, stainless steel, aluminum, copper, or other metal tubing.
A mandrel bender offers enhanced support within the tube by incorporating a mandrel—a metal rod or flexible series of balls—inside the tube during bending. This specialized tooling prevents wrinkling, collapse, and ovalization, particularly when producing tight-radius bends or working with thin-walled, stainless steel, or non-ferrous tubing. Mandrel tube benders are recognized for their ability to achieve high-precision bends suitable for critical applications such as hydraulic lines, fuel pipes, and exhaust systems.
Common mandrel types include the plug mandrel, formed end plug mandrel, standard mandrel, thin-wall mandrel, and ultra-thin wall mandrel. The choice of mandrel depends on tube diameter, material, desired bend radius, and wall thickness.
Hairpin benders are specialized tube bending machines engineered to create 180° bends—also known as hairpin bends—in coiled copper and aluminum tubing often used in HVAC and refrigeration systems. Advanced automation uncoils multiple tubes and aligns them precisely in the working track. The automated conveyor transports the tubes to the bending section, where mandrels and robotic clamping dies facilitate simultaneous, repeatable 180° bends over a bending die. Post-bending, the system withdraws the mandrels, cuts the bent tubes to custom lengths, and collects them for assembly or further processing.
Modern hairpin benders deliver exceptionally high production rates by leveraging chip-less cutting and programmable automation, significantly reducing material scrap and labor costs, and increasing productivity and manufacturing efficiency.
Return benders function similarly to hairpin benders but are optimized for producing U-tube shaped fittings—known as "return bends"—that redirect fluid flow by 180°. Frequently employed in heat exchangers, boiler coils, and chiller systems, these industrial tube benders uncoil spooled tubing and leverage internal mandrels to support and form the 180° bend. Return benders ensure dimensional consistency and critical alignment for mass production of HVAC and process industry components.
Crossover benders offer greater versatility compared to return or hairpin benders, as they can accommodate a broad spectrum of tube diameters and bend angles—not limited to 180°. These programmable tube fabricating machines are ideal for creating crossover bends, short straight tubes, elbows, and return bends for intricate piping or structural designs. Their adaptable tooling and quick-change setups enable rapid transitions between production runs while maintaining tight tolerances.
Press benders utilize opposing dies and a ram to apply precise forming force to the tube, shaping it directly to a predetermined angle and radius. This tube forming method is widely applied for making symmetrical bends in steel pipes and tubes and is suited for lower volume or less complex production. Press bending is a cost-effective alternative to rotary draw bending when high precision or tight radii are not mandatory.
Angle rollers (roll benders) feature three rollers in a triangular or pyramid arrangement, enabling gradual and uniform bending of pipes and tubes with large radii. These machines excel at bending long sections of round tubing, square tubing, rectangular pipe, and structural profiles, allowing for spiral, circular, or helical shapes. Roll bending is often chosen for architectural, infrastructure, and ornamental metalwork projects.
Freeform angle rolling allows for real-time radius adjustments, supporting custom fabrication of rings, coils, and spirals. This method is ideal for large-diameter tubes or when consistent radius bends are required over long lengths.
Tube spinning, a form of precision flow forming, stretches and elongates tubing to alter its wall thickness and mechanical characteristics. During tube spinning, the tube is mounted over a mandrel and drawn along its axis by synchronized rollers positioned around its circumference. The process may be performed externally—stretching the tube over a solid mandrel—or internally, spinning tubing within a hollow mandrel. Tube spinning is frequently utilized in the aerospace and energy sectors to manufacture seamless tubes with consistent properties and variable diameters.
This technique is valued for its ability to enhance the tensile strength and grain structure of tubes, making it suitable for applications where high-performance and thin-walled tubes are required. The process also reduces material waste and accommodates workpieces of varying diameters and lengths.
Shear spinning is a high-precision metal fabrication process that applies compressive and tangential forces to shape tubing while reducing its wall thickness and preserving its diameter. By stretching the tube material over a mandrel, shear spinning increases depth and densifies the crystal structure, thereby enhancing the tubing’s strength and durability. This advanced forming technique is ideal for manufacturing aerospace components, fuel tanks, domes, and pressure vessels where uniform wall thickness and superior structural integrity are demanded.
Careful management of friction and temperature via lubricants or coolants is required in shear spinning to maintain surface finish and tooling life, especially with high-strength metals like stainless steel or titanium.
Deep drawing is a fundamental tube and pipe forming method, pivotal in creating seamless tubes and custom-diameter pipes for automotive, energy, and industrial applications. This drawing process forms hollow cylinders from sheet metal or pre-existing tube by forcing the material through a die, sometimes in multiple reduction stages. The four principal deep drawing approaches are:
Tube sinking (also tube drawing) involves pulling a tube through a die, setting the outer diameter and reducing the wall thickness. It is commonly applied for producing precision seamless tubing in steel, stainless steel, and non-ferrous alloys, widely used in industries like medical devices and heat exchangers.
In the floating mandrel process, a loose mandrel creates balanced forces inside the die, enabling wall thickness adjustments during tube drawing. This flexible technique is used for manufacturing variable-thickness tube sections for specialized machinery or custom applications.
The fixed mandrel deep drawing method pulls both the mandrel and tube through the die simultaneously, controlling wall thickness and inner diameter. It’s preferred for applications requiring precise internal tolerances such as high-pressure hydraulic or pneumatic lines.
Moving mandrel deep drawing draws a cylindrical mandrel along with the tubing, efficiently reducing the tube wall to achieve the desired thickness and strength. This approach is used for production of seamless pipes with exact interior and exterior dimensions.
Pilgering is a specialized tube reduction process used for achieving substantial reductions in both diameter and wall thickness—often exceeding 90% in a single pass. Both hot pilgering (for alloy, stainless, and refractory metals) and cold pilgering (for tight-tolerance applications) involve a set of ring dies and a tapered mandrel. The process forms seamless tubes with superior surface finish, tight roundness, and exceptional concentricity—key characteristics for nuclear, aerospace, oil and gas, and critical pressure piping systems.
Modern pilgering machines use advanced controls to synchronize die movement, tube rotation, and feeding, enabling manufacturers to meet demanding quality standards for high-performance or exotic alloy tubing.
Autofrettage is a pressure-based tube enhancement technique designed to increase fatigue strength and resistance to stress corrosion cracking. By applying carefully controlled hydrostatic pressure, the interior layers of the tube are plastically stretched beyond their elastic limit, while outer layers remain within elastic deformation range. This induces a residual compressive stress state in the inner wall and boosts the load-bearing capacity of pressure vessels, hydraulic cylinders, and high-performance piping often used in the oil, gas, and defense sectors.
Some autofrettage processes also incorporate low-temperature heat treatment to promote metallurgical changes, further enhancing material performance and long-term reliability, even under extreme operating conditions.
Tube end formers, or end formers, are machines used in shaping the tube typically on or near its end. End formers create an installation port on the tube for other media (e.g., hoses, blocks, or another tube). Formed ends enable tubes to fit with other mechanical parts. For fluid conveying applications, it ensures that no fluid will leak from the connection. It also changes the fluid velocity by increasing or decreasing the flow area.
The axis of the tube remains unchanged after the process. End formers can alter the geometry of the tube end in various ways:
Reduction and expansion refer to the decrease and increase of the tube end’s cross-sectional area, respectively.
Beading is the process of creating protruded "beads" near the end of the tube. These beads serve multiple purposes: they act as mechanical stoppers when the tube is fitted with other parts, enhance the effectiveness of seals, facilitate the connection of a tube to a hose, and strengthen the tube's end. Additionally, they help dampen vibration in solid lines.
Flaring is the process of forming joints on two tubes, so they produce a leak-proof seal when fitted to each other. Double-lap flared tubes have thicker material on their inner diameter; this offers additional strength and fatigue resistance and reduced variation in the flow area. Special types of flared joints include Marmon bead flares and spherical ball flares.
Flanging involves flattening the material at the end of the tube to create a flange that is seamlessly integrated with the tube.
End forming machinery comes in various types, including ram formers, segmented end formers, and rotary forming machines:
Ram end formers shape the tube end by applying axial force to induce material deformation. These machines feature vise jaws and a ram nose. The vise jaws clamp and support the tube while one end is being formed. Positioned next to the unsupported end, the ram nose, which contains the final shape of the tube end, strikes the unsupported end to induce deformation. This process is repeated with different ram noses over several strokes, gradually achieving the final shape. Due to the heat and friction generated during each stroke, lubrication and coolant are typically applied.
Ram end formers can produce tube ends in various shapes, both symmetrical and asymmetrical, depending on the tooling geometry. They are particularly useful for applications requiring significant expansion or reduction.
During a beading operation, the tube is positioned in a clamp with a gap between its halves. These clamp halves feature spaces for forming the tube bead. The bead is created as the clamp halves push each side of the tube towards each other in the axial direction. When beading is performed using a ram former, it is referred to as compression beading.
Segmented end formers work by applying radial force to the circumference of the tube to induce material deformation. These machines use a circular die divided into segments that apply the radial force. Unlike ram forming, segmented end forming usually does not require a clamping mechanism.
In the case of compression, a radial force from the outside of the tube squeezes it, reducing its cross-sectional area. Conversely, during expansion, a tensile radial force from the inside stretches the tube, increasing its cross-sectional area. The radial force application is repeated over a specific number of strokes, with the segments rotating slightly to ensure uniform deformation of the workpiece.
The common types of tooling used in segmented end formers are C tooling and inside/outside (I/O) tooling. C tooling can perform either expansion or reduction operations. I/O tooling offers greater flexibility, featuring two concentric circular segmented dies between which the tube is fed, allowing it to carry out both functions.
Rotary end formers use a rotary head to modify the tube’s cross-sectional area by applying either tensile or compressive radial force. The rotary head is equipped with three to four cylinders that move axially through the tube, either on the inside or outside, while applying radial force. Rotary end formers can create flaring with angles ranging from 20° to 90°.
Tube hydroforming and tube swaging machines alter the cross-section of the tube at various points along its length.
Tube hydroforming is a process that uses highly pressurized fluid to expand metal tubes against the inner walls of a mold, altering their cross-sectional shape. This technique is versatile, accommodating tubes and hollow sections of various shapes. Tube hydroforming machines can transform stock tubes into complex and irregularly shaped sections.
To start the tube hydroforming process, the stock tube is placed between the mold halves of the hydroforming machine, which are then closed with sufficient clamping force. The length of the stock tube should be slightly longer than the cavity length. Sealing rods with internal presses are inserted at both ends of the tube, which is then filled with water. The internal press, powered by thrust actuators, compresses the fluid inside the tube. The resulting high internal pressure causes the metal tube to expand into the mold cavities. Finally, the hydroformed tube is ejected from the mold.
Hydroformed tubes offer high stiffness and seamless connections, enhancing their strength. The cost-effectiveness of tube hydroforming increases when used to form large tubes.
Tube swaging is a tube forming process designed to reduce and shape the cross-section of a tube. It can also alter the tube's cross-sectional shape. Essentially a forging process, tube swaging involves forcing the tube through and compressing it with a confining die to achieve the desired shape. The types of tube swagers are as follows:
In rotary swagers, a motorized spindle with reciprocating dies is enclosed within a cage that holds pressure rollers surrounding the spindle. As the spindle rotates, centrifugal force pushes the dies against the pressure rollers, causing the dies to move inward and close. The alternating open and closed positions of the dies compress the tube into the desired shape as it passes through the cavity of the rotating dies. A mandrel can be inserted to support and aid in shaping the tube.
Rotary swagers can be either two-die or four-die machines. Two-die swagers are typically used for smaller parts and offer a better surface finish. Four-die swagers are employed for larger parts, especially when significant initial reductions are required.
Long die swagers, a category of rotary swagers, are designed to create extended, shallow tapers.
In stationary spindle swagers, the dies exhibit a reciprocating action similar to that of rotary swagers. However, in this setup, both the spindle and the forming dies remain stationary while the head rotates and drives the pressure rollers. Because the forming dies are fixed in place, stationary spindle swagers can reshape a tube’s cross-section into different or asymmetrical forms.
In die-closing swagers, a segment of the tube to be swaged is inserted through a set of closed reciprocating dies before the swager begins rotating. The wedges then advance to compress the dies. A radial compressive force is applied each time the die strikes the tube for a set duration. After the swaging process is complete, the dies retract, and the swaged part is removed.
Tube cutting machinery is a category of tube forming machines designed to either reduce or divide the length of a tube or remove some of the tubing material through cutting. Tube cutting typically serves as an intermediate step in other fabrication processes.
Some examples of tube cutting machinery include:
Tube threading is the process of creating helical ribs on the end of a tube or pipe to facilitate assembly with other tubes or parts with threaded ends. It does not alter the tube’s cross-section or axis and is not considered an end forming process.
The tube stock is inserted and clamped by the jaws on the center of the tube threader’s wheel. These jaws are locked to prevent the tube from slipping. Prior to threading, burrs on the tube end are removed in a process known as reaming. If the tube threader lacks a reaming tool, this step is performed by a separate deburring machine.
To create the thread, material is cut away from the tube end using a stationary universal die head equipped with sharp teeth. The universal die head is adjusted to match the outer diameter of the tube. Once setup is complete, the wheel rotates the tube while the universal die head is placed on the tube end. Cutting begins as the sharp teeth engage with the tube. Liquid coolant is applied to the cutting area, and the chips generated from cutting are collected on the bed of the tube threader.
Tube and pipe notchers are used to reshape the ends of tubes by removing a portion of the material, enabling them to be mounted on other tubes and mechanical parts. Notched tube ends are often welded to create joints for structural applications. Side-notched pipes, for instance, facilitate the fabrication of tee fittings used in fluid flow branching.
There are several types of tube and pipe notchers, including end mill notchers, punch-type notchers, and plasma notchers. End mill notchers remove material from the tube using a sharp, rotating mill positioned perpendicularly at its end. Punch-type notchers apply a shear force to cut the tube end using a punch. Plasma notchers utilize a jet of ionized gas to melt and cut the tube end, making them more practical for cutting large sections compared to the other types of notchers.
Tube slotters are used to remove a portion of tubing material to create slots. Slots can be formed using a press, where a punch strokes the tube and applies shear force to cut the material. Mandrels are used to support the tube internally during the cutting process. Additionally, slots can be created through machining or laser cutting methods.
Tube deburring removes excess metal from the tube end, polishes it for a smooth finish, and improves the aesthetic quality of the tube.
In a brush deburring machine, the tube end is sanded by a brush with rough and abrasive bristles made from thin metal wires. The brush is attached to a rotating element, such as a rotating disc or cylinder, which scrapes off the unwanted material from the tube end while the tube remains fixed during the process.
Tube cutting is the process of cutting a tube to its desired length. Various types of tube cutting machines are available for this purpose:
A cold saw machine uses a circular toothed blade to cut the tube to a specific length. The blade can be made of solid high-speed steel (HSS) or tungsten carbide-tipped (TCT). It is powered by an electric motor that rotates the blade. A coolant is sprayed on the cutting section of the tube to reduce friction and heat. Cold saw machines generate minimal friction and heat during cutting, resulting in a longer blade life.
In band saw machines, the toothed blade is made from a continuous band of thin, sharp metal. The blade rotates around two wheels and is cycled in one direction. The orientation of the cutting plane, whether horizontal or vertical, is determined by the arrangement of the wheels. The tube is placed on the bed of the band saw machine and fed towards the blade.
Band saw machines are ideal for large-volume production and can cut tubes with various cross-sections. However, they are not suitable for thin-wall tubes.
Supported shear cutting machines use internal punches and external dies to cut the tube. Stationary and movable punches are inserted into the tube to provide internal support during cutting. The tube is clamped between external dies, which include both stationary and movable dies. The movable punch and die apply shear force to cut the portion of the tube between the stationary and movable components.
Dual blade shear cutting machines are designed to cut carbon steel and alloy steel tubes while eliminating the dimple produced by single-blade cutting machines. These machines use a horizontal blade to make an initial scarfing cut on the side of the tube. Following this, a vertical blade continues the cut from the notch created by the horizontal blade. Throughout the process, the tube is clamped tightly by a set of tooling.
In rotary cutting machines, the tube is supported on two backup rollers, while a rotating blade is fed from the top and descends to cut the tube.
In lathe cutting machines, the tube is fed through a chuck-type clamping mechanism that rotates the tube while feeding it to the cutting tools. Alternatively, the setup may involve a stationary tube with rotating cutting tools surrounding and cutting the tube.
Laser cutting machines use high-energy solid-state or CO2 lasers to melt the tubing material, allowing for quick and precise cutting of the tube into the desired length.
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