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Tube End Forming Technology: Shaping the Future of Heat Exchanger Manufacturing

Heat exchangers are vital technologies utilized in HVAC systems, refrigeration, power plants, chemical processing, and commercial & industrial facilities globally. The production of heat exchangers relies on advanced metal forming techniques like tube end forming to create the thousands of high-integrity joints required. Here, we will explore tube end forming and the machines that enable this essential process for heat exchanger manufacturing.

Copper and aluminum tube ends machined by a tube ending machine

What is Tube End Forming? 

Tube end forming, also referred to as tube end shaping or tube end swaging, is the process of altering the geometry of tubular metal workpieces to prepare them for joining. Using radial compression, tube ends are precisely enlarged, reduced, flared, expanded, extruded, or contoured as needed to facilitate joining operations.

Common methods for tube joining include mechanical expansion, brazing, welding, and proprietary techniques. By pre-forming the tube ends, tight leak-free joints can be efficiently mass-produced in heat exchanger assembly.

Tube materials used include copper, brass, carbon steel, stainless steel, aluminum, nickel alloys, titanium, and exotics. Workpiece sizes range from micro-tubes under 1 mm up to large diameters exceeding 50 mm. 

Tube end forming is an efficient cold working process allowing high production rates and minimal material loss. It produces geometries that cannot be effectively machined or cut and enhances material properties through cold working.

Popular profiles include bulges, beads, flares, extrusions, inverted shapes, and more. The appropriate profile and dimensions are determined based on the tube material, wall thickness, and end joining method.

Tube End Forming Processes

The two most prominent processes used are rotary swaging and radial forming. Hybrid machines combining both techniques are also common.

Rotary Swaging:Uses two or more dies, which radially compress the tube walls as they rotate around the tube. Swaging displaces material to form the desired profile. It allows generous deformation while maintaining concentricity.

Radial Forming:Presses profiled dies straight into the tube end to displace material. Radial forming permits precise control over internal dimensions. Hybrid machines use radial forming for pre-forming, followed by swaging.

Other valuable processes include spin forming, push forming, and cam forming. Advanced CNC tube end-forming machines can integrate multiple forming capabilities.

Tube End Forming Machines 

Dedicated tube end-forming machinery is essential to repeatable, high-quality production. Key types of tube end-forming machines include:

➢Rotary End Formers:Rotate tube workpieces between stations for in-line forming. Highly productive with speeds from 10 to 60 tubes per minute.

➢Linear End Formers:Use inline stations without rotation. Provide precision forming for delicate tubes. Lower throughput than rotary.

➢CNC End Formers:Utilize programmable servomotors and controls rather than cams. Allow quick changeover and flexibility.

➢Standard End Formers:Use manual die changeovers and analog controls. Well-suited for high-volume runs with one profile. 

➢Bench Top End Formers:Compact machines for low volume or laboratory use. Production rates under 10 tubes per minute. 

➢Hybrid Machines:Combine both rotary and linear process capabilities for versatility.

➢High-Speed Formers:Robust industrial machines focused on ultra-fast cycle times.

In addition to end-forming stations, these machines incorporate material handling like tube feeds, hoppers, and conveyors to automate production. Advanced controls and changeover capabilities minimize setup time between jobs.

Bobo Machine's Automatic Five Stations Tube End Forming Machine

Tube End Forming Applications

Tube end forming is utilized in the manufacturing of various critical components and assemblies, including:

➢Heat Exchangers:Used extensively in HVAC and refrigeration, power generation, chemical processing, cryogenics, and more.

➢Medical Devices:Key for implants, surgical tools, catheters, endoscopy equipment.

➢Hydraulic Cylinders:Requires formed tube ends to accept attachments and seals.

➢Dairy & Food Equipment:Critical for sanitary tubing networks transporting milk, liquids, and refrigerants.

➢Aerospace:Utilized in engine components, fuel systems, and structures using exotic alloys.

➢Furniture:Forming used for structural tubing in chairs, tables, and frames.

➢Automotive:Exhaust headers, fuel lines, air conditioning components.

For manufacturers in these industries, tube end-forming machinery is indispensable for achieving necessary production volumes, quality standards, and profitability targets.

Long copper tube ends machined by a tube ending machine

Conclusion

Tube end forming is an indispensable process that empowers the production of remarkably complex heat exchanger designs. This metal shaping technique crafts tube ends with unparalleled precision and efficiency, enabling them to be joined into intricate internal structures.

Advancements in tube end-forming tech will drive innovation in heat exchangers and manufacturing. With machines delivering ever-greater accuracy, changeover agility, and high-volume output, engineers can fabricate state-of-the-art heat exchangers to drive progress.

Continuous improvements in automated tube end formers will remain mission-critical, allowing manufacturers to stretch limits and enable technologies of the future. Tube end forming sits at the intersection of quality, efficiency, and engineering creativity. The full potential of next-generation heat exchangers relies on optimizing these transformative fabrication machines.

Frequently Asked Questions

Automatic Tube End Forming Machine

What tolerances can tube end forming hold?

Precision end formers can hold tolerances of +/- 0.1 mm or tighter. Factors include machine rigidity, die wear, and tube material. Secondary processes may further improve tolerance.

What is the typical cycle time?

On high-speed rotary end formers, cycle times can be as fast as 0.6 seconds. Smaller and more complex parts may range from 2-10 seconds, depending on the machine.

Do end formers require special power or infrastructure?

End formers typically run on standard 3-phase electrical supplies. Some machines may require compressed air. Installation requires level flooring that can withstand vibration and load.

How are tube end-forming machines maintained?

Preventative maintenance includes lubrication, cleaning, inspection for worn components, hydraulics service, and monitoring/replacing worn dies.

How long do tube end forming dies last?

Die life depends on use, materials, and maintenance. Carbide dies generally last the longest. Lubrication and rotating dies help distribute wear. Dies may last hundreds of thousands to millions of cycles.

What safety equipment should be used with end formers?

Tube end formers should have safety guards, interlocks, E-stops, and fencing to protect operators. User PPE includes eye protection, gloves, sturdy shoes, and avoiding loose clothing.

How does end forming prepare tubes for joining?

End forming creates profile shapes that allow tubes to be securely joined through processes like brazing, welding, mechanical expansion, flaring, and proprietary attachment methods.

What are some common tube end profiles produced by end formers?

Common profiles include bulges, beads, flares, inverted shapes, square shapes, and custom geometries. The appropriate profile depends on the tube material, wall thickness, and joining method.