Tube Bending and Forming

Metal tube bending has a wide variety of applications in numerous industries. Learn how bending and forming tubes takes place using precision engineering and proven techniques designed to withstand numerous functions.

A wide variety of industries rely on tube bending and forming to create equipment and other materials including, but not limited to:

What is Tube Bending?

Tube bending describes the process used to form metals and other types of materials into tubing or pipes. The processes by which metal tube bending takes place may involve a variety of methods using temperature, equipment, and materials. For the purpose of this resource, we are focusing on metal tube bending and forming.

The materials involved in metal tube bending often fall into two categories—either the materials are ferrous (primarily made from iron) or non-ferrous (metals coming from elements other than iron). Ferrous materials used in bending include steel, stainless steel, or steel alloys. In the case of steel alloys, a mix of steel with another metal is done for the purposes of avoiding corrosion of the materials as well as making the metal stronger.

Tube bending and forming involves more than just welding metal into various shapes and uses. It uses a variety of techniques tailored to the needs of the manufacturer and requires accuracy in design and development. Some tube bending and forming might involve a tube mill or a roll forming machine, depending on the application intended for the tubing.

Types of Tube Bending

There are a number of ways metal tube bending can take place. Generally, tube bending falls into two types – form-bound tube bending and freeform tube bending.

Form-bound tube bending describes a bending technique whereby the bending contour is dependent on the tool geometry and so shapes the piece of metal into the shape of a die (which is similar to a mold in that it is generally custom made for its intended application). Form-bound tube bending can be done manually in instances where a specialized piece needs one or several engineers to shape it the way it needs to be, or it can involve machinery to bend it into the intended shape.

Types of form-bound tube bending include rotary draw bending, compression bending, and mandrel bending.

Freeform tube bending, on the other hand, describes bending that does not intend to conform to the shape of a die. This is usually done through tube bending technology and presses that run the metal through the process of bending the pipe in a fluid motion without any breaks. This is helpful for materials like roll over cages where one continuous piece of a section is shaped.

An example of freeform tube bending includes roll bending where pipe or tube passes through three rollers set in a pyramid structure to shape the tube.

Both form-bound tube bending and freeform tube bending can employ Computer Numerical Control (CNC) machinery to precisely control the tube bending and forming process.

Other Tube Bending Terminology

Rotary Draw Bending: This method of form-bound tube bending includes usage of dies and other components to draw tubing into the machinery and create the desired bend. Rotary draw bending can also use mandrel bending, as explained below.

Mandrel Bending: A mandrel is a rod, usually cylindrical in shape, that can be placed inside of a metal tube and help shape it during the tube bending process, with the goal being to avoid defects in the bend such as rippling, flattening, or collapse of the tube. Mandrels are especially effective when the material being bent has thinner walls.

Compression Bending: A tube bending method where two dies are used – a die that stays stationary, and a counter die that bends the tubing around that die in order to achieve the desired shape.

Roll Bending: When the tube bending process requires large radius bends (bends in which the radius bend is eight times that of the material’s thickness), roll bending might be required. Rollers shaped into a pyramid configuration, or dies that can accommodate the large radius bends, usually facilitate this process.

What is Tube End Forming?

Tube end forming describes the process by which some kind of connection to another media—such as a tube, hose, or block—can be used in tubing applications.

Tube end forming applications can be used in a variety of industries where tube bending and forming is needed, such as the automotive industry where a variety of media is used and creating a leak-proof environment is critical to functioning machinery.

Process of Tube End Forming

Tube end forming involves machinery to establishing a secure connection and can include one of many categories, such as:

  • Reduction tube end forming – A process where the tube diameter is reduced using dies and tapered rings, depending on the application.
  • Expansion tube end forming – A process where the end of the tube is expanded to fit one tube end into another. This application might be necessary in heat pump assemblies, healthcare equipment, and other uses.
  • Beaded tube end forming – A process where beads are added to the end of the tube in order to strengthen a tube and/or to hold a hose on the other end.
  • Flare tube end forming – A tube end forming process where a tight seal is formed at the end of the tube.
  • Thickening tube end forming – A process where, as the name suggests, the tube end is thickened.

Contact Our Metal Tube Bending and Fabrication Company

If you have questions about tube bending and forming, or are looking to partner with a leading team of engineers on your project, contact Bohn and Dawson today.