How to Avoid Common Tube Bending Problems

Even minor tube bending problems can cause scrap, rework, or poor part performance. Issues like wrinkles, crimping, and deforming often result from preventable oversights. Our article outlines how to identify common bending difficulties and what steps to take to avoid them.

Even though the tube bending process seems straightforward, it involves a precise balance of pressure, alignment, and material control. No matter how small, inconsistencies can lead to unwanted defects like wrinkling, springback, or flattening. These types of problems are really widespread. For example, even tube bending experts often search for queries like: how to prevent crimping when bending pipes?

That is why we have outlined the most common tube bending problems and provided practical ways to prevent them. Whether you're bending tubing manually or using a CNC setup, understanding the source of the individual faults is the first step to getting consistent, clean results.

Identifying the Most Common Tube Bending Problems

Most tube bending issues fall into a few recognizable categories. While they may appear different on the surface, many share the same causes, such as improper tooling, poor setup, or pushing the material beyond its limits.

Here are the most frequently encountered problems:

Crimping or Kinking

• Occurs when the tube folds or collapses on the inside of the bend
• Often caused by too tight bend radius or insufficient internal support

Wrinkling

• Tube bending wrinkles show up as wave-like deformations on the inside radius of the bend

• Typically results from a greater clearance between the inner diameter of the tube and the outer diameter of the mandrel or due to insufficient pressure being applied by the pressure die or due to a wrong rake angle of the wiper die

Deforming or Flattening

• Happens when the tube loses its round shape, becoming oval or flattened
• Common when wall thickness is too thin or the tooling isn’t properly matched

Excessive Springback

• The tube tries to return to its original shape after bending
• More likely with stronger or harder materials if not compensated for in the setup

Scoring or Scratches on the Tube Surface

• Can be caused by galling or cold welding on the tube surface during bending
• Is often caused by using inadequate tool materials

Tube Slippage while Bending

• Insufficient clamping pressure between the clamp and the bend die
• Common if a correct gripping solution is not used during tool manufacturing

These issues need to be recognized early and having a solid understanding of their causes makes it easier to prevent them in future bends.

Wrinkling is an often-occurring tube bending problem

How to Correct Specific Tube Bending Faults

While tube bending problems can be frustrating, most are correctable with a few simple adjustments to tooling or setup. Below are some typical faults and straightforward ways to address them.

Crimping or Kinking

• Use a mandrel with correct clearance as internal support to achieve bending tubing without kinking
• Check the wall thickness of materials since thinner walls need more internal support

Wrinkling

• Add or adjust a wiper die to smooth the inside of the bend
• Tighten clamping pressure to hold the tube firmly in place
• Slow down the bend speed to allow for better material flow

Deforming or Flattening

• Match tooling radius and tube diameter more precisely
• Ensure proper alignment of die and clamp
• Use bending tools made from low-friction materials to reduce drag

Springback

• Overbend slightly to compensate for material memory
• Adjust tooling pressure to maintain the intended bend angle
• Use test bends to establish correction factors for different materials

Scoring or Scratches on the Tube Surface

• Select tools made from materials suitable for tube bending
• Adjust the linear movement of the pressure die to match the bending speed

Tube Slippage while Bending

• Use correct gripping solutions like serrations or special gripping solution to avoid slippage
• Take care during the tool design and select an optimum clamping length and the correct gripping solutions

Correcting these faults early in the process doesn’t only reduce waste, improves repeatability, and ensures that finished parts meet design specifications.

Components made of specially engineered alloys eliminate several tube bending problems

Best Practices to Achieve Consistent Output

Besides fixing individual tube bending problems, consistent quality comes down to a reliable setup, good material choices, and dependable operating procedures. Whether working manually or with automated equipment, some of the best practices include:

Starting with the right material

• Use tubing with uniform wall thickness and proper surface condition
• Avoid damaged or out-of-round stock, which can lead to unpredictable results

Regular calibrations of the tooling

• Make sure all dies, clamps, and mandrels are properly aligned and in good condition
• Check for wear that could affect bend accuracy or surface quality

Utilizing controlled bending speeds

• Bending too fast can lead to wrinkling or springback or tube slippage while bending
• A steady, moderate speed allows better control over the material

Monitoring and adjusting as needed

• Run test bends before production
• Make small adjustments to correct for material behavior or batch variations

Choose low-friction tooling materials

• Using tooling made from specialized alloys helps reduce wear, protect the tube surface, and improve bend quality
• For example, aluminum bronze tooling is often used to help avoid galling and deformation

Building consistency into the process not only improves part quality but also helps reduce downtime, rework, and material waste.

Using a customized setup guarantees optimal tube bending results

Final Thoughts

Even though some tube bending problems are common, they almost never are random. Most issues can be traced back to the same set of causes, and using the right setup, tools, and with proper attention to detail, they’re almost entirely avoidable. By recognizing the signs early and applying a few proven corrections, it’s possible to produce cleaner bends and reduce costly rework.

If you are curious about how material choice and tooling design can further improve tube bending results, you can explore more in-depth resources or get in touch with our expert team.