Tube bending is critical in industries like automotive and aerospace, but challenges such as wrinkling, collapse, and spring back can impact quality. Understanding these issues and their solutions is key to achieving optimal results. Learn about common problems and effective troubleshooting techniques to enhance your tube bending processes.
Tube bending is an essential process in many industries, from automotive to aerospace. However, it comes with its own set of challenges. Wrinkling, collapse, wall thinning, ovality, humps, springback, and breakage are common problems that can affect the quality and functionality of bent tubes. Understanding these issues and their solutions is critical to achieving optimal results.
What is tube bending?
Tube bending involves manipulating a straight tube into a curved shape without compromising its integrity. This technique is critical in applications ranging from the design of automotive parts to the manufacture of aircraft components.
It is widely used in industries such as automotive, aerospace, shipbuilding, construction, and medical device manufacturing. Each industry relies on precise and durable bends to meet its specific requirements.
Types of tube bending
There are several methods of tube bending, each suitable for different applications:
- Rotary Draw Bending: Commonly used for precise bends, this method uses a rotating die to form the tube.
- Roll bending: Uses rollers to form large-radius bends, ideal for creating smooth curves.
- Mandrel bending: Uses a mandrel inside the tube to prevent collapse and ensure accurate bends.
If you want to learn more, here is an interesting article on the different types of tube bending.
Common issues
When bending tubes, several problems can affect the quality of the final product. Here are some common problems and their typical causes:
- Wrinkling
Wrinkling can occur throughout the bend or in portions of the bend. It is often caused by poor tool quality or inadequate support. Adjustments such as moving the wiper die closer to the tangent, reducing the rake of the wiper die, and increasing the pressure die's pressure can help alleviate this problem. If wrinkling occurs only in parts of the bend, it may be due to an out-of-round bend die or a taper in the pressure die.
- Collapse
Collapse during tube bending can either be excessive or occur after removing a ball mandrel. Excessive collapse is often the result of an undersized mandrel or poor-quality tooling. Solutions include advancing the mandrel toward tangency, adding more balls to the mandrel, and adjusting the die force. If collapse occurs after removal of the ball mandrel, it is usually due to excessive drag on the tube, which can be prevented by reducing pressure die force and improving mandrel support.
- Spring back
Springback is the tendency of the material to return to its original shape after bending. To control this, you can check the ductile strength of the tube and program an overbend to compensate for springback.
Troubleshooting techniques
Consider the following techniques to effectively troubleshoot tube bending issues:
- Wrinkling
For wrinkles throughout the bend, moving the wiper die closer to the tangent, reducing the wiper die rake, re-cutting worn wiper dies, and increasing the pressure die's pressure can be effective. For partial wrinkles, adjust the stripper rake angle and use high-quality tooling.
- Collapse
To prevent excessive collapse, advance the mandrel toward the tangent, add more balls to the mandrel, and adjust the pressure die force. For collapse after ball mandrel removal, reduce die force, increase stripper rake, and improve mandrel support.
- Spring back
To control excessive spring back, check the ductility of the tube and program an overbend to compensate for the material's tendency to return to its original shape.
There can be many other tube bending problems such as wall thinning, ovality, bumps, breakage, and more. In our technical paper we have listed all the possible problems and how to solve them. Check it out!
Best practices for tube bending
At AMPCO METAL, we understand the complexities of tube bending and offer a range of solutions to effectively address the issues listed above. Our high-performance copper-based alloys are designed to provide excellent wear resistance, high strength, and superior performance under load, making them ideal for tube bending applications.
Our high-performance alloys are designed to reduce common problems such as wall thinning and fracture. These alloys offer improved durability and can withstand the rigors of the bending process, ensuring consistent quality and longevity of bent tubing.
We also offer custom solutions to meet specific bending requirements. By working closely with our customers, we develop alloy solutions that address their unique challenges, optimize their bending processes, and reduce material waste.
For further information about tube bending, please download our free technical paper «Troubleshooting common tube bending issues – a material guide»
