How Do I Flare a Tube?

THE FLARE: Perhaps one of the most common tube end-forms in the tube world, the flare is a relatively simple form. There are many machines and methods to get the job done. Flared tubes are used in nearly every industry, be it a hydraulic line for a tractor, a fuel line for an airplane, or a transition on a leg for a table.

The two primary methods of flaring are ram forming and rotary forming.

RAM FORMING: Ram forming involves the tube being gripped in a set of clamps while a cylinder with a tool comes forward and forces the tube to open up. The tool is a pointed taper cut to a degree to match the flare angle. The back of the clamps have a matching taper which supports the outside of the tube. When the ram comes forward, the material is pushed from the inside out until it touches the back of the clamps. The ram returns and the clamps open and the part is removed.

ROTARY FORMING: Rotary forming uses similar tooling (clamps and a pointed tool), but instead of a ramming force, the rotary machine uses a rotating arbor to push the material sideways from the inside out. The material is clamped in a set of jaws that have the desired taper cut into the back. An arbor with a matching taper enters the tube while the arbor is spinning. Once the arbor is inside the tube and spinning, a cylinder pushes the arbor to one side. The off-center arbor rotates around inside of the tube, pushing the material into the taper cut in the back of the clamps. At the end of the cycle the arbor returns to center, the clamps open, and the finished part is removed.

Both options are used around the world and have advantages and disadvantages depending on the material, diameter, size of flare, etc. At AM Industrial, we stock both options for sizes of tubing from 1/8” up to 8” and larger. Feel free to call us to discuss your project and what machine will best meet your needs!