Bending Processes and Applications

An overview

When it comes to bending pipe or tube, there are several techniques that can be used to achieve a quality, custom-formed part. Given the variety of methods and variables, it’s important to know the options that go into creating the end product. Using one of these methods, along with the right machine technology, most customer job specifications can be met in an efficient manner.

The primary types of bending used for tube and pipe are: compression bending, roll bending, freeform bending, and mandrel bending (also called rotary draw bending), which the most common method. Here is more detail about each of these processes:

Compression Bending
This is a simple method of bending pipe or tube where the bend die stays stationary while a counter die bends or compresses the material around the stationary die. This method requires a bend die that is the size of the desired bend radius. The material is then formed around the bend die, without the use of a mandrel.

Roll Bending
Roll bending is typically used for large radius bending. In this process a piece of pipe or tube rotates through a three rollers that are in a triangle configuration. The two outer rollers, usually stationery, cradle the bottom of the material while the inner roller, which is adjustable, presses on the top of the material. This method is ideal for large radius bends and is best suited for producing large, wide radius sweeps.

Freeform Bending
Freeform bending uses one set of tooling to bend variable or multiple radii. Normally pipe and tube bending requires a bend die, a clamp die and a pressure die and sometimes a wiper; with freeform bending the material is continuously guided through the machine using one die that is the size of the pipe or tube being bent. Most any radius can be achieved using a single die set.

Mandrel Bending or Rotary Draw Bending
Most tube and pipe bending is done using a mandrel, an aluminum-bronze alloy or solid steel insert that supports the pipe or tube while it is being bent. This common technique keeps the tube from collapsing, flattening or wrinkling during the bending process. A mandrel also helps to ensure accuracy of the end product by maintaining the shape of the tube.

Within this discipline is also multi-radius bending, which is commonly used for complex parts when one continuous pipe or tube requires two or more center line radii. It is a good fit for parts with a large centerline radius, where hard tooling may not be an option or for complex parts that need to be formed in one complete cycle.

In addition to knowing the options for your project, it is also important to understand how product design can impact lead times and labor. Discussing the scope of your project at the beginning stages can help know what’s involved in the manufacturing process. For further information or to discuss an upcoming project, contact a product specialist today.

This blog was compiled and researched by Kristen Crump, Marketing Manager, Sharpe Products. Kristen can be reached at kristenc@sharpeproducts.com.