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Wrinkles in Tube Bending: Getting the Right Bend with Mandrel Tube Bending Services

by Last updated Nov 12, 2020 | Published on Jan 2, 2018Pipe & Tube Bending

Estimated Reading Time: 3 minutes

You need tubes bent. This seems like a simple enough task to do on your own, since you have equipment that will do the job onsite. Here’s what happens: Your technician places the tube into the mandrel tube bender without checking the thickness of the tube or setting the die pressure at the right spot. When the tube is bent, there is wrinkling along the inside bend radius.

For OEMs in certain industries, such as semiconductor fabrication or medical device production, wrinkles on bent tubes are not tolerated for a variety of reasons. A wrinkle can cause fatigue to both metal and plastic material, as it can lead to cracks or material failure if the tube is placed into an assembly that experiences high amounts of pressure from liquids or gases.

Unfortunately, wrinkling is a common defect when bending tubes and pipes. Understanding the reasons why this defect occurs, and finding the right solutions to prevent the issue can ensure your tubing is bent at the highest quality.

What Causes Wrinkling?

With mandrel tube bending, using a mandrel is supposed to avoid the issue of wrinkling along the inside of pipes and tubing. The mandrel is designed to stay in a fixed position as the outer radius of the tube experiences pressure; this pressure causes the pipe to stretch into the desired bend.

Wrinkling of the pipe can occur for numerous reasons. It could be as simple as having the pipe slip from the clamp while it is under pressure, or the mandrel was not pushed up into the pipe far enough to provide a smooth bend. Another common problem is that there simply wasn’t enough pressure used. Other issues can include not having the wiper die in the right position; the wiper die being worn; not using the right amount of lubrication; or having too much clearance between the mandrel and the pipe.

Solutions to Wrinkling

Since there are a wide range of reasons why you may be seeing wrinkles from inexpert tube bending, you may have to experiment to determine the actual issue. One of the first things that people typically do is to increase the tube pressure. It stands to reason that, with more pressure, there won’t be room for the tube to wrinkle as it should remain smooth throughout the draw.

However, if you increase the pressure and still experience wrinkling, then you will have to take additional factors into consideration. Checking the mandrel insertion rate, the amount of lubrication in use, and the condition of the wiper die may also eliminate the issue.

Or, you may find that you are using the wrong mandrel for the type of metal you are trying to bend. Always remember to use a soft mandrel when bending hard tubing and a hard mandrel when bending soft tubing.

Reliable Pipe Bending Outcomes

Because of the number of defects that can be introduced during the pipe and tube bending process, it may be more cost effective – and easier – to hire a reliable component manufacturing company like Axenics. By doing that, you reduce material waste. Our expert technicians can ensure the correct bend, every time,  based on years of technical experience. Our equipment is also re-calibrated and serviced regularly to ensure our results are accurate every time.

Another important advantage to obtaining tube bending services from contract manufacturing companies such as Axenics is that we have a Class 100 cleanroom to ensure every pipe and tube is bent using a clean process, should that be necessary for your industry or operation. This service is desired by OEMs in a range of industries where tube contaminants have the potential to ruin assembly systems or end products. By having your pipe or tube bending services performed by Axenics, you get a reliable and durable bent tube that meets your specifications every time.

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