In industrial tube bending technology, there are numerous processes that are used in different ways depending on the requirements and area of application. Two of the most commonly used methods are mandrel bending and rotary draw bending. Both methods have their own advantages and specific applications. In this article, we at Tinsel highlight the differences between these two techniques to help you decide which method is best suited to your production.

1 What is mandrel bending?

Mandrel bending is a technique in which a mandrel is inserted into the pipe to support the pipe from the inside while it is bent around a shape. This prevents kinks, pinches or creases from forming on the inside wall of the pipe. The mandrel ensures that the pipe retains its shape during bending, even with tight radii.

Advantages of mandrel bending:

• High precision: Thanks to the support of the mandrel, even complex and tight bends are possible without deforming the pipe.​
• Ideal for thin-walled pipes: Particularly suitable for thin-walled pipes that could easily kink or buckle without a mandrel.​
• Clean bends: Minimizes distortion and ensures smooth, clean bends without wrinkling.​

Disadvantages of mandrel bending:

• Longer set-up time: Inserting the mandrel requires additional time and precise adjustment, which extends the set-up time.​
• Restriction for pipe diameters: Mandrel bending can be complicated and less effective with very small or large pipe diameters.​

2 What is rotary draw bending?

Rotary draw bending is a method in which the tube is placed in a rotating bending mold and bent to the desired angle by pulling. No mandrel is used here, which simplifies the process. This method is particularly suitable for tubes with larger radii and is often used in automotive and furniture production.

Advantages of rotary draw bending:

• Fast production: The method is relatively fast and efficient as no additional tools such as a mandrel are required.​
• Easier handling: Less complex machines and set-up times, making the process more economical, especially for series production.​
• Wide range of applications: Well suited for larger bending radii and thick-walled pipes that are less susceptible to kinking or deformation.​

Disadvantages of rotary draw bending:

• Limitation with tight radii: Without the support of a mandrel, creases or deformations can occur on the inside of the pipe with tight radii.​
• Not ideal for thin-walled pipes: Without support, thin-walled pipes tend to collapse or develop unclean bends.​

3. Areas of application of mandrel bending

Mandrel bending is often used in industries where precision and tight radii are required. These include

• Automotive industry: Mandrel bending is often used for exhaust pipes and complex lines that require tight bends.​
• Aviation and aerospace: In hydraulic and fuel systems that require high precision.​
• Furniture production: For curved metal frames where a clean look and structural strength are important.​

4. Areas of application for rotary draw bending

Rotary draw bending is suitable for industrial applications where large production quantities and less tight radii are required:

• Vehicle construction: For bending frame and body parts that do not require tight radii.​
• Pipeline construction: Especially for thick-walled pipes used in pipeline or pipe networks.​
• Furniture industry: For larger bends in chair or table frames that need to be produced quickly and efficiently.​

5. Conclusion: Which procedure is right for you?

The choice between mandrel bending and rotary draw bending depends on the specific requirements of your production.

• Mandrel bending is the best choice if you need to process tight bending radii or thin-walled tubes. It offers maximum precision and quality, but requires more effort in terms of set-up time and handling.​
• Rotary draw bending, on the other hand, is ideal if you are looking for efficiency and high quantities and want to bend larger radii. It is particularly suitable for thick-walled pipes, where the risk of deformation is lower.​

At Tinsel, we offer a wide range of tube bending machines that support both mandrel and rotary draw bending. Our experts are available to help you select the right machine for your specific needs.