How to Troubleshoot Square Tubing Bending

Fix the problems that can make square tubing a hassle.

Square tubing is especially problematic to work with because it can easily lose shape at the bend when being outfitted for a particular job. Knowing potential problems ahead of time can prevent you from wasting valuable materials. Square tubing, which comes in aluminum, metal, tin and a variety of other materials, can be used for guide rails, sign posts and athletic equipment. Some of the methods used to bend square tubing include ram bending, mandrel bending and ring roll bending, and each can come with its own set of problems.

Things You'll Need

• Mandrel tube bender
• Sand

Instructions

1. Check the fit of the tube in the mandrel. Using a mandrel to bend square tubing means that the tube has to be properly loaded and secured, if not, wrinking or breakage could occur. If the tube is not held securely by the clamp die and it slips or you're not using enough lubrication, you could experience breakage. If your mandrel is not far enough forward or you use too much lubrication, wrinkling could occur. Also, maintain adequate pressure on the pressure die to prevent the pipe from slipping on the bend die.

2. Look at the orientation of the weld seam. If you've experienced splitting at the seam where two sections of your tube have been welded together, you may be bending with the seam too far away from the inside bend. It is safer to load the tube with the seam in a neutral position at the top or on the inside of the bend directly against the bend die. Also, if your tube is rectangular and not a perfect square, it's safer to bend with the thin side against the die.

3. Use enough support in your tubing. If you find yourself with a kink at the bend point, you need more support through the center of your tube while you bend it. If you're not using a mandrel, use one. This will support the bend. Another option, if you don't have access to a mandrel, is to fill the tube with water and freeze it. The ice will support the bend. You can also fill the tubing with sand before you bend it.

Tips & Warnings

• If possible, use thicker materials for less distortion. Rotary bending and compression bending are better for smaller tubing.

• If you heat tubing before bending it, check the specifications for your material to determine how much heat to use and for how long, to avoid damage.

References

• Speedy Metals: Typical Applications
• Ocean Machinery: Pipe and Tube Bending Methods
• Baliegh Industrial: Bending Square and Rectangular Tubing
• Hines Bendgin: Basic Tube Bending Guide