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Bending rectangular tubing

bending rectangular tube
bending rectangular tube

What is rectangular tube?

RHS steel sections ( RHS beams ) also called rectangular tubes are just one of three types of popular steel hollow sections.

RHS beams are popular in mechanical, structural, and construction applications because they typically have a very flat structure that makes it more economical for welding, joining, and various other types of fabrication work.

Definition: In short, what is RHS? RHS beams are a type of rectangular steel tubing. They only need to be straight-cut when joined to other flat services. This makes the RHS section very popular, as very little welding and joining preparation is needed. They are also used to glam up the look of a building, as they are very straight and smooth, as well as strong.
Rectangular tube bending is the same as rectangular tube bending for the profile bending machine. The difference is that the bending parameter size is determined according to the bending height.

Bending rectangular tubing is a more difficult process than round tube bending (all else being equal: surface area, radius, wall thickness, material type, etc.).

How to bend rectangular tube

Bending rectangular tubing is a more difficult process than round tube bending (all else being equal: surface area, radius, wall thickness, material type, etc.). As with almost all metal bending processes, the tighter the bend, the more difficult it becomes. Similarly, bending rectangular tubing with thinner walls is more difficult than bending thicker walls (provided the bending machine has the power to curve the thicker sections).

5 ways to bend rectangular tubes

Bending methods are the same for round, square, and rectangular materials:

  • Rotary draw bending
  • Induction bending
  • Roll bending
  • Increment bending
  • Compression bending

As with all bent parts, the customer’s tolerances and appearance requirements help determine the proper method.

Hard Way (X-X Axis) Or The Easy Way (Y-Y Axis)

Rectangular Tube and Square Tube, sometimes referred to as HSS. Rectangular Tubing can be rolled either the Hard Way (X-X axis) or the Easy Way (Y-Y axis).
Other pitches of roll (off-angle rolling) can be achieved with special tooling. In general, the thicker the wall, the less distortion is achieved by the rolling process.
Radius also plays a crucial role about distortion. The tighter the radius, the more distortion is to be expected.
Bending rectangular tubing the hard way: Acceptable distortion limits should also be determined and agreed upon before commencement of any project. AESS standards are generally the most stringent.

bending rectangular tubing the hard way
bending rectangular tubing the hard way
bending rectangular tubes
bending rectangular tubes
The difference between the hard way and the easy way

Regarding the direction of the bend, although more pressure is required to bend a tube the hard way, the curved member is less likely to distort because it is more rigid than a section curved the easy way. Easy-way bending often results in the inside diameter becoming somewhat concave.
Bending a rectangular tube the hard way produces less distortion or concavity than bending the easy way especially when the difference between the sides of the tubing is greater. There is a greater chance for distortion in the larger tubes bent to a smaller radius than for the smaller tubes bent to a larger radius.

8 parameters of bending rectangular tube
8 parameters of bending rectangular tube

8 parameters of bending rectangular tube

There are several parameters to know for performing tube bending:

  1. Radius for the bend section – CLR
  2. Chord of the bend section – C
  3. Arc length – L
  4. Degree of bend – a
  5. Rise of bend section – R
  6. Tube size – D
  7. Wall thickness – t
  8. Tangents – A, B
  9. Not all are necessary to be known but at least three are needed to produce a correct tube bend.

Even though procedures are the same for bending all tubes, square-end rectangular tubes require special consideration.
After the information is collected and analyzed, the appropriate method of bending is chosen. All this information is key for choosing the appropriate method of tube bending which may be rotary draw bending, the more parameters are known, the better the bending method can be chosen which will produce the best final results: accurate bends without distortion.

bent rectangular tubing

5 points for attention in bending design

Several methods exist to support the inside of the tube to achieve tighter radii.

  • The location of the weld seam and the corner radii are required for proper mandrel fitting into the inside of the tube.
  • For shop-fabricated materials square or rectangular corner edges become work-hardened which may cause difficulty bending.
  • Bending round, square or rectangular tubes requires stretching the outside diameter of the bend and compressing the inside diameter.
  • The heavier the wall thickness, the tighter the bend radius that can be achieved with less distortion.
  • If tubes are to be architecturally exposed then more consideration is required to produce a clean bend.


rectangular tube bending machine
rectangular tube bending machine of the mandrel

Tips For Bending Steel Tubes:

However, there is some troubleshooting to do when performing steel tube bending.

Bends often require achieving a tight radius. Since the outer wall of the bend becomes thinner, the result may be a distorted bend. To prevent this, using a mandrel to give support is recommended. That is also why press or ram bending is not recommended in these situations. The most adequate bending method would be mandrel bending, which is the same as rotary draw bending, but adds a mandrel to support the inside of the pipe.

The machine in the picture above can bend the rectangular tube after changing the mold. Of course, it supports the bending of the mandrel.
Sometimes the radius we need to achieve makes the steel exceed its elastic limits. It can result in deformation in the form of a hump or wrinkles. To prevent the formation of humps and wrinkles, it is recommended to use rotary draw bending or three-roll bending.

Four Types of CNC Rectangular Tube Bending Machines for Cold Bending

When bending stainless steel tubes and pipes, it is important to remember that some stainless steels require around 50% more power for bending than carbon steels. Therefore, the machinery must be set accordingly.

Further reading: The difference between tube and pipe

square tube bending machine

PHB & MS Series Rectangular Pipe/Tube Rolling Machine

BIT PHB & MS square pipe/tubing rolling machine can roll bending square pipe/tube into a circle or arc.

  • Width (mm): 30-350
  • Height (mm): 20-350
  • Wall thickness (mm): 2-12

More detailed parameters
Note: A larger size square pipe/tubing roll bending machine can be customized

square aluminum tube bending machine
Aluminum Square Tube Bender

PHA CNC Aluminum Rectangular tube/pipe bending machine

Roll bending aluminum tubing.
Can be bent in various shapes (3-D graphics, C-shaped, U-shaped, full circle, ellipse, multiple radii combination shapes, etc.). Suitable for bending aluminum profiles for automobiles, doors, and windows.

  • Max. Section. Width (mm): 50-300
  • Max. Section. Height (mm): 70-500
  • Y-axis thrust (ton):10-70


cold pipe bending machine

PBT CNC Rectangular Tube Bender

BIT PHB & MS square pipe/tubing rolling machine can roll bending square pipe/tube into a circle or arc.

  • Width (mm): 18-168
  • Height (mm): 18-168
  • Wall thickness (mm): 2-14
  • Bending radius range (mm):25-750
  • Maximum bending angle (°) :0-200
  • Core length (mm):1800-5000

More detailed parameters

aluminum c channel bending machine

aluminum Rectangular tubing/pipe Bending Machine

Small aluminum profile bending machine with excellent performance, the main bending L-shaped, rectangular, U-shaped, and other shapes.

  • Max. Section. Width (mm): 100
  • Max. Section. Height (mm): 200
  • Punching mechanism repeat positioning accuracy: < 0.01mm Spindle rated.
  • Spindle speed: 1-15r/min
  • Min bend radius: R=40mm

More detailed parameters

Related Reading: Similarities Between Bending Round and Rectangular Tubing

PBH Rectangular Tube Bending Machine

PBH series section bending machine can bend square hollow sections for structural projects including curved formwork, barrel vaults, roof trusses, and bridge rails.


The roll bending of the rectangular tube is the same as the roll bending of the round tube, but the mold is different.

The picture below shows the rolling and bending molds for rectangular and round tubes:

BIT’s rectangular tube bending machine, also known as square tube bending machine, profile bending machine, or section bending machine, has a compact structure, generous appearance, low noise, low energy consumption, and high efficiency, no noise, compact structure, It has the advantages of simple operation, easy maintenance, convenient installation and use.

 ModelSpecification (mm)Minimum Inside Diameter (mm)
PBH-12065 × 61000
PBH-14090 × 51500
PBH-200100 × 62000
PBH-300120 × 83000
PBH-360150 × 85000
PBH-450180 × 106000
PBH-500200 × 108000
PBH-550250 × 1210000
PBH-600300 × 1215000
PBH-700350 × 1230000

Working principle of the rectangular tube rolling machine

The rectangular tube rolling machine is mainly composed of the main machine, the hydraulic station, and the electric control cabinet.

The high-pressure oil output by the electric oil pump is sent into the working oil cylinder or the motor through the high-pressure oil pipe, and the high-pressure oil pushes the plunger in the working oil cylinder or the motor to generate thrust and torque and then bends the profile through the mold parts.


  1. Small size and lightweight: Because not only does the new technology transmission structure, but the input shaft and output shaft are on the same axis, this machine has the characteristics of a compact structure, small size, and lightweight.
  2. High mechanical efficiency, fewer failures, and long service life. The main transmission engaging parts of the rectangular tube bending machine are made of high-quality composite steel, and the work roll end bearing is supported by ZWZ bearings, which have a large load-carrying capacity and reduce power loss caused by friction. Therefore, mechanical performance is Good, with good wear resistance, coupled with the use of rolling friction, so that it has fewer failures and long life.
  3. The operation is reliable and stable. The transmission process of the BIT series rectangular tube rolling machine (section bending machine) is multi-tooth meshing, so it runs smoothly and reliably. Low noise.
  4. Convenient disassembly and assembly, easy maintenance, adopts an integral structure, reasonable design, strong rigidity, simple disassembly assembly, and easy maintenance.
  5. BIT series rectangular tube rolling machine (section bending machine) also has strong overload capacity, impact resistance, and small moment of inertia, suitable for frequent starting and forward and reverse rotation characteristics. Improve the service life of the motor.
  6. It has the advantages of strong carrying capacity, long life, fast winding speed, reliable product quality, and so on.
  7. Safe operation, high rolling efficiency, convenient adjustment, long service life, low energy consumption, and good economy.


  • The type of square tube to be rolled: square tube or rectangular tube; such as 20 × 20 or 20 × 40, etc.
  • How to bend a rectangular tube, such as a 40 × 60 rectangular tube, a flat-rolled 40 with a face elevation of 60 will save effort (easy way), and a flat-rolled 60 with a face elevation of 40 will make it more powerful (hard way), the choice of equipment should also use a larger model of equipment.
  • Rolling method: three types are commonly used, one is round or a large arc. The second type is to bend as an angle, any angle within 180 degrees. The third category is the spiral coil.
  • For coiling a single circle or a large arc, please choose a three-roller (section bending machine). For any angle within 180, please choose an NC rectangular tube bender. Most of the spiral coil pipes use a CNC profile bending machine or multi-roller.

The above rectangular tube bending machines BIT are all produced, and we will recommend equipment according to your bending needs.