Pipe bending is one of the most commonly used processes in most fabricator workshops. From making roll cages to frames of furniture, bending the pipe is essential for every application when it comes to metal fabrication processes.
There are multiple ways to accomplish tube bending, from bending it by hand (which is impractical for most requirements) to using a hydraulic pipe bending machine that is specially designed for the job.
Even among pipe bending machines, the choice is astonishingly high as there are so many different types of pipe bending machine available in the market.
In this article, we will learn about different types of pipe bending machine. You will also know the advantages and disadvantages of each type, along with which industry utilizes it.
What are the Different Types of Tube Bending Methods?
There are ten types of pipe bending techniques that are used by professionals. Each of these methods comes in a variety of implementations. For instance, in some methods, hydraulic systems are used to move the dies. In others, movements can be accomplished by electric servomotors or by manual means.
The different types of tube bending methods are:
Press bending is one of the simplest types of pipe bending processes. In press bending, two dies that contain the shape of the bend are pressed against the pipe that requires bending. When these pressure die are pressed against the pipe, the shape of the bend is imprinted on the pipe.
- Cost of bending is cheap.
- Fast bending speed
- It is not a versatile process. You cannot change the shape of the bend without changing the dies themselves.
- Press bending has very poor accuracy.
- It often leads to the crushing of the pipes completely.
Rotary Draw Bending
Rotary draw bending is one of the most common tube bending processes due to the precise bends it creates. It is a complex process where the tube is clamped on its outer diameter and bent around a bend die. The radius of the bend die is the same as the required radius of the bend.
Rotary draw bending is one of the most widely used tube bending processes. It is used for making roll cages, furniture frames, handrails, and many other applications.
- Highly accurate bends
- High precision
- Rotary draw bending creates bends at high speed
- Rotary draw bending has an expensive setup cost
- For different shapes of bend and tubes, you need different tooling
Compression bending is a bending method of the past and is rarely applied nowadays. In compression bending, the pipe is clamped at both ends, and pressure is applied at the point of the required bend, so the bend moves into space.
Compression bending is generally used in the construction sector for the bending of electrical conduits.
- Compression bending is fast
- Simple tool setup
- Pipe can get damaged or even break
- It is only applicable for pipes of limited diameter
- Not applicable for small radius bends
In roll bending, a series of rollers push the pipe through a coil of the required bend angle. Generally, 3 to 4 rollers are found in the roll bending machine. Roll bending machines can be used to create coils of pipes and truss rod bends.
Roll bending is mainly of two types:
Three Roll Push Bending (TRPB): TRPB is a good option when you require a tube with several bending curves. The pusher can rotate the tube along its vertical axis, so the bends can be formed in different planes.
Simple Three Roll Bending: As the name implies, simple three roll bending is a basic version of TRPB. It just pushes the tube and bends it, without the ability to form bends in different planes.
- You can bend different tube sizes without changing tooling
- Option to create multiple bends in different planes
- The process is very slow as compared to other bending techniques
- It requires multiple hit and error trials for good accuracy
- High chances of damaging tubes in case of small bend radius or thin tubes.
Mandrel Tube Bending
Mandrel tube bending is not a solo bending technique, but in fact, a modification of other bending techniques such as rotary draw bending. Mandrel bending is applied to hollow tubes and involves placing internal support in the tube to protect it from collapsing during the bending process. The internal support is generally a solid metal bar of a slightly smaller diameter than the workpiece tube.
Mandrel bending is a very common bending technique. It is used for creating exhaust pipes for automobiles, aerospace equipment, and exercise equipment.
- Better accuracy
- Protects the tube from damage
- High repeatability
- Requires a longer setup time
- Increased costs
Wiper Die Bending
Just like mandrel tube bending, wipe die is another modification of the other bending processes like rotary draw bending. In this technique, a die called wiper die is placed beside the bending die to prevent the formation of wrinkles and exceeded flow of material of the tube.
- Avoids tube deformation and formation of humps
- Increases the setup time
- Increases the cost of bending
Heat Induction Bending
As you might know already, metals are easier to shape at high temperatures. Heat induction bending follows this concept. In heat induction bending, a heated coil is placed near the tube to increase the tube’s temperature, ranging from 800-2200 degrees F.
When the required temperature is obtained, the tube is bent by holding it with a clamp and applying force with a pivot die. It may be followed by cooling the tube with water or allowing it to cool naturally.
The heat induction bending method is usually applied for the creation of pipelines in the petrochemical industry. This method is also used in the large radius components that you see in the construction industry, as well as in the power distribution sector.
- Heat induction bending requires less bending force
- It allows for the bending of tubes of high wall thickness
- It can damage the structural integrity of the pipe
- High temperature can create visible stains on the pipe
- The dimensions of the pipe and bend can vary after cooling
Sand Packing and Hot Slab Forming
Sand packing and hot slab forming is a combination of multiple techniques. First, the pipe is filled with sand and closed at both ends. Then the pipe is heated in a furnace to a high temperature. After that, it is held on a slab with pins at both ends and bent around with force from a winch or crane.
- The sand makes sure that deformation of material is minimal
- The high temperature allows for easier tube bending with less force requirement
- The process works well for tubes of high wall thickness
- It is a hot tube bending process, which can cause thermal strain on the material
- The dimensions of the bend after cooling can vary
- The tube bending time is very long
Ring Roll Bending
Ring roll tube bending is applied to metal strips of minimal wall thinning instead of tubes and pipes. Metal strips are formed into curved bands with machines called ring roll bending machine. These curved bands can then be joined together through welding to form rings.
- Cheap process
- Simple and easy to use
- Applies to thin metal strips only
In ram bending, the tube is placed on stationary dies called counter dies, which are placed at an angle relative to the bend angle required. A pressure die then applies a force to the tube and creates the required bend.
Ram bending machinery is suited for projects that do not require a high tolerance level.
- The process is simple and easy
- Tube bending cost is less
- Fast bending
- Ram tube bending can cause the tube to collapse
- The process is not very accurate
Important Factors to Consider When Choosing Tube Benders
When considering which type of tube bending technology and machine to use for your next project, there are certain factors you should keep in mind. These include:
Budget can be the primary factor limiting the choice of tube benders. There are always better technologies available, but whether or not they will fit your budget is something only you can decide.
The accuracy provided by different bending techniques can vary by day and night. Check how precise you require your bends to be. Certain requirements, like fitting a roll cage inside your car, can call for a high degree of precision.
3. Workable Size
Certain methods work for thin tubes well, while certain are good for bending thick tubes and pipes. Choose a method that works well for the tube thickness that you intend to bend.
4. Bend Angle
Methods like ram tube bending work for small bend angles, while rotary draw tube bending can bend large angels very well too. Therefore, if your requirement calls for large bends, invest in an appropriate machine that facilitates the same.
If you want to get the best value for your money, you can check out the range of top-of-the-line tube benders provided by RogueFab. These benders are available at different price points, and never compromise with build quality regardless of which one you buy.
There are many different tube bending methods and technologies to choose from. Before you go ahead with a particular one for your project, make sure it is the best one suited for you.
Using the wrong method can not only damage your raw materials, but it can also cause physical injury to yourself as well. It is always a good idea to go an extra mile in quality instead of risking your pipes, time, and safety in a method that isn’t up to the mark.