shutterstock_Tube Bending

What is Tube Bending?

Tubing gives manufacturers a more significant structural advantage compared to piping. Faster installation and cheaper pricing are reasons to choose tubes instead of pipes.

 

We need a proper channel to transport fluid from one location to another. Tubes help us do just that for various requirements and conditions. The most common material used for tubes is copper due to its long length and strength. 

 

However, the outlet and destination may not always be in straight lines. Hence, straight tubes are unusable in most cases. This is why tubes need repurposing to support fluid transportation across different elevations and terrains. 

 

There are other uses for bent tubes, such as frames, structures, etc. Cutting or welding may weaken the structural integrity of the tube. So, how can you reshape tubes so that they retain their materialistic properties and still be of use? Let’s take a look.

 

Tube Bending Defined

Tube bending is a metalworking process used to bend tubes into a useable shape or form. This fabrication method works primarily with metals and alloys but is not limited to any specific material.

 

In tube bending, the resulting shape is permanent. When a tube is bent, the outer wall of the tube elongates and thins. Since no material is lost during the process, the inner wall compresses and thickens. The objective of tube bending is to create a smooth round bend.

 

The engineering team designs the required shape, and it is then fed into machines or manually deformed by skilled workers using suitable tools. Tubing is a go-to solution to tackle strict regulations and increasing stresses on fluid systems.



What Are the Different Types of Tube Bending?

Tube bending is a rich science, and there are different approaches to achieving the intended result. It varies depending on the quality of material, function of the end product, and resources at hand. Listed below are the most common types of tube bending. 

 

Press Bending

Press Bending is the oldest industrial tube bending method. The tube is fixed at both ends, and a bend die is pressed against the tube. The resulting bend's characteristics depend on the bend die's external dimensions.

 

Press bending is relatively fast and useful for symmetrical parts, and it can be done without lubrication or cleaning. 

 

The limitation of this method is the inability to form a smaller degree. It is difficult to control and can only help if a consistent cross-section is not needed. 

 

Rotary Draw Bending

Rotary draw bending is suitable for creating precise bend angles with constant center-line radius and diameters. It is useful on hollow tubes with different cross-sections, giving minimal ovalization.

 

This method is complex and requires a specific toolset to bend the tube. The tube is rotated around the bend die and is held by a clamp and pressure die. To prevent wrinkles, a wiper supports externally, while a mandrel does the same internally. 

 

Compression Bending

In compression bending, the set-up is more straightforward and cheaper compared to rotary draw bending. Suitable only for circular hollow sections, compression bending does not use a mandrel for internal support and can therefore flatten the outer surface a bit. It is commonly used to bend symmetrical tubes for structural application.

 

Roll Bending

Roll bending is useful in creating bends with large Center Line Radius (CLR) for larger components and is popular in structural applications. You can also bend tubes into spirals or coils by re-positioning the tube after one revolution. 

 

Three rollers, two stationary and one moviable are set up in a triangular shape. The stationary rollers rotate opposite to the moving roller’s direction while the tube moves back and forth. 

 

Heat Induction Bending

Heat induction bending produces bends with a wider range of CLR. It does not require compression dies or mandrels. Due to its accuracy, the induction bending technique is applicable in mining, energy, and petrochemical industries.

 

This method holds the tube at the front end while the bend clamp is placed amidst the rotating arm and the rear end. The tube is gradually moved towards the bend clamp and passes through an induction coil that supplies heat tangential to the bend radius. The pivot, in which the front of the tube is clamped, is approximately equal to the required bend radius. The working temperature is dependent on the chosen material, and the final workpiece is cooled down using an air or water spray.

 

Use cases

1. Automotive Industry 

Used in exhaust systems and to make roll cages for race cars, off-road vehicles, and ATVs.

 

2. Aerospace Industry

It is used to increase structural integrity in space vehicles and relevant components.

 

3. Manufacturing Industry

Used to make machinery and tools and is a backbone of the manufacturing industry.

 

4. Construction Industry

Cranes, skyscraper frames, and other structural components are designed using tube bending.

 

5. Furniture & Recreation

Used to make furniture frames for beds and tables and outdoor recreation furniture, including, collapsible beds, chairs, and tents. 

 

A tube bend is permanent, and its geometry depends on the tooling, tubing material, and amount of lubrication. It experiences tensile stress on the outer diameter, which elongates, and compressive stress on the innermost surface, thickening it in the process. However, operators must follow safety regulations, ensure minimum material wastage, and choose the correct method as per requirement.


At MMI, we have helped leading brands leverage our extensive network and sub-brands to overcome manufacturing and supply chain challenges. Our decades of experience will help you bring products to market on time both domestically and abroad.

 

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