July 5, 2021

Unison Ltd Blog – Your tube bending problems solved

In this week’s Unison Ltd blog, we take a look at common problems you can face in tube bending and how to resolve them.


Problem – Hump at the end of the bend

Adjust the Mandrel slightly back from the Centreline until the hump is barely visible.

Increase the force on the Follower to push material past the Mandrel.

Multiple bent parts
Some of our perfectly bent tubes

Problem – Tool marks on the Centreline of the bend in the Clamp and Pressure Die area

Reduce the force on the Clamp and Pressure Die.

Check for oversized tube or an undersized tube groove.


Problem – Tool marks on Centreline of the bend

Check the vertical alignment of your Clamp and/or your Pressure Die.

Check for oversized tube or an undersized tube groove.

Find out more about our tooling here.


Problem – Wrinkling throughout the bend extending into the Wiper Die area

Move up your Wiper Die forward so it is closer to the Centreline. Also, decrease the rake angle of your Wiper Die.


Problem – Deep scratches throughout the bend in the Wiper Die area 

Increase the rake angle of the Wiper Die and check to see if you have an undersized Mandrel.

Make sure you increase the amount of lube used during your bend and reduce the force on the Pressure Die.


Problem – Wrinkles throughout the bend area, even if the Mandrel and the Wiper Die are in a known good position

Mandrel is almost certainly undersized. The smaller the Radius as a ratio to Diameter (D) the more important it is to be a tight fight, also the lower the Elongation properties the tighter fit it needs to be.

Sometimes increasing the Pressure Die force can compensate for poor fitting mandrel

Reducing the Powered Follower force can also compensate for poor fitting mandrel


For more advice or information on tube bending, get in touch with our experts here.

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