Want to get started on tube bending in your shop? Know the basics


Tube bending refers to the action of remodeling tubing and piping into certain shapes and designs. This process plays an important role in the manufacturing and transportation of materials. Tube bending offers a number of advantages and these advantages have a lot to do with supporting the tubular work pieces. Unlike other metal forming processes, tube bending is precise, so each work piece can be produced as accurately as possible. Unique structural designs can be created. What is more, defects can be completely avoided.   

Bending tubular work pieces is a skill that is passed from craftsman to apprentice. So, what do you do if you want to do tube bending? If you want to take up metal fabrication and get the opportunity to earn business, you will have to learn the basics. It is true that technology has evolved a great deal over the last couple of years, but tube bending still remains a simple one. As a matter of fact, the basic principles have not changed for decades.

Fundamental Terms in Tube Bending

The metal forming process starts with understanding the properties of the cylinders you are working with.

  • Centerline Radius (CLR)

This term designates the radius of the bend or the curve. When touching upon the radius of a bend, you are referring to the CLR. Centerline radius is the distance between from the center of the bend to the centerline axis of the pipe or tube. When you have to choose the right CLR for the tubular work piece, consider minimum wall thickness specification and design.  

  • Outside Diameter (OD)

Tubing is frequently described in terms of outside diameter. The OD stands for the distance traversing to the extreme outside dimensions.

  • Wall Thickness

Every tube or pipe has a wall thickness. Wall thickness represents the distance between the outside diameter and the inside diameter. Tube bending is a lot more easier when there is heavy wall thickness. To measure wall thickness, you can use calipers.

  • Elongation

This is the extent to which a cylinder can stretch prior to failing and even cracking. Elongation takes place during the bending process, usually causing wall thinning. As a manufacturer, you should be concerned about material stretching.

How Tubes Bending Is Achieved

When a cylinder is arched, the wall that forms the outside of the arch stretches and, at the same time, the wall that forms of the inside thickens. Your goal is to form a smooth round curve. Therefore, you need to be able to control these degrees of physical deformation. You should do what all tube bending services do, namely measure the wall thickness. To see if the wall is thin or sturdy, compare its thickness to the outside diameter.  Equally important is to use the correct die because if the tubes or pipes do not fit into the die, you will end up with poorly finished products. Internal wall compression may occur, so you should better use a wiper die to reduce the risk of wrinkles. The wiper die is made in such a way that it prevents the deformation of the wrinkles that typically occur.

Common Types of Tube Bending

There are many types of tube bending styles, each one having particular advantages. Here are the most common types of metal forming processes used to form tubular work pieces.

  1. Press-Type Bending

The machine used in this process is like a press machine, the only difference being that it is specifically designed for the sheet metal pressing industry.  The form of the bend is pressed against a pipe until it fits the shape of the curve. Press bending is mostly used in the automotive industry because it contributes to good parts formation.  

  1. Compression Bending

This metal forming process involves using various machines to create bends for large tubes and pipes. It is often used for making spiral shapes. A compression die is used to flex the work piece around a stationary die. What the compression die does is tighten the cylinder against the central band die. Compression bending is used mainly to manufacture exhaust pipes.

  1. Rotary Draw Bending

It is a very precise technology, which is the reason why it is used for producing tight radii. The outside radius is effectively supported and you have complete control over the machine in terms of thinning and ovality. What is more, you can program the rotary draw bender to store jobs with various degrees of curving.

Tube vs. Pipe – The Difference Explained

If you are genuinely interested in bending tube or pipe in your shop, you have to learn what you are bending. Permanently forming a tube is not the same thing as permanently forming a pipe. The outside diameters vary, so you will need a different die for each size. A tube is called by the outside diameter, while a pipe is mainly called out by its inside diameter. Tubing is mostly used for structural purposes, while piping is used for transporting gas and fluids.

Get good tools and materials

Having the right materials is important. As a rule, make sure that you have both hard and soft material. If you want to have a successful business, you need to acquire proper tooling too. No matter what you want to bend, you need die sets, mandrels, and wipers. The dies absorb the shock without breaking. The best choice of material is steel. Concerning the mandrels, focus on hardness. If you have a hard cylinder, you need a hard mandrel and vice versa. As for wipes, consider the setup, not the material specification.

Now you have a basic idea about what tube bending. Do you think it is worth getting into tube bending? As you can see, forming pipes and tubes is not rocket science, but neither is it easy. Instead of involving yourself in metal fabrication, you are better off leaving the job to competent designers. Even the most competent professionals have trouble when it comes to metal forming. To cater to the needs of your clients, hire tube bending services.