Tube bending is a metal forming process that permanently bends or changes the shape of tubes and pipes. There are multiple different types of tube bending processes, such as cold forming, heated metal bending, free-form bending, and form-bound procedures. Precision tube bending is a slow, carefully managed process that requires specific tools and honed skills to properly bend the tube without damaging it.
Stainless steel tubing, whether welded or seamless, can be curved and bent into precise shapes; however, seamless tubes respond best to tight radius bends. Here, we will discuss the various considerations when bending stainless steel tubing as well as the different tube bending methods.
Considerations When Bending Stainless Steel Tubing
Before bending stainless steel tubing, there are many variables and structural considerations that must be taken into account. These include:
- Material Thickness. The thickness of the pipe’s walls affects the final product. Thicker walls require more force to bend, while thinner walls may be easier to crack or wrinkle.
- Welded Tubing. Welded pipes have a seam that can interfere with the consistency of the bend. The weld itself may have also been improperly formed and cause the tube to not be perfectly round.
- Bend Radius. Tighter bend radii require more careful application of force. Depending on the thickness and inner diameter of the pipe, a 180° bend may be possible, but it may require a wider “U” shape to preserve the interior shape and structural integrity. The radius also determines what types of equipment can be used to handle the job; three-roll benders typically handle pipes with a large bend radius, whereas mandrel tube bending processes perform tight radius operations.
- Applications. Stainless steel tubing can be used in applications that need to meet high standards of sanitation, including food processing and pharmaceuticals manufacturing. However, the material can’t be contaminated by carbon during the metal forming or transportation process.
Methods for Bending Stainless Steel Tubing
One of the most common methods used for bending stainless steel tube and pipe is rotary draw bending. The radius of such bends is often described as, for example, “2D.” A 2D bend is one whose center-line radius is equal to two times the outside diameter of the pipe to be bent. Rotary draw bending involves clamping on the outside diameter of a pipe and drawing it over a bend die whose radius matches the desired bend radius. Rotary draw bending can employ an internal supporting mandrel and a wiper die to prevent wrinkling on the inside wall of a tight bend. Some rotary draw machines can perform both push bending and rotary bending with a single tooling setup.
Another common method for forming stainless steel tube and pipe is rolling. In this process, rollers move tubing over or around a die, putting enough pressure on the material to force the tube into the shape outlined by the die. This process needs to be handled slowly and smoothly to minimize stress on the metal and reduce the risk of cracks and deformation.
Another common method for forming stainless steel tubing is compression bending. In this process, a roller compresses the tube against a die. To protect the internal shape of the tubing, operators can insert mandrels into the pipes. These help the tubing hold its shape so it doesn’t collapse or pinch.
Other methods include ram bending, which uses a hydraulic ram to push the stainless steel tube against the rollers; and rotary draw bending, which uses a pressure die, a clamp die, and a round bend die to shape the tubing. Rotary draw bending can create accurate, intricate shapes, so it’s a preferred option for creating consumer and commercial goods.
Partner With E Tube & Wire for Expert Stainless Steel Tube Bending
Stainless steel tube bending processes can transform straight lengths of pipe into virtually any shape. However, tubing with different characteristics and intended forms or applications needs to be carefully matched with the right processes.
At E Tube & Wire, we specialize in high-quality stainless steel tube bending processes. We provide CNC mandrel tube bending services to meet the needs of various industries, including food processing, automotive, refrigeration, and more. For more information, or to get started on your stainless steel tube bending solution, contact us or request a quote today.