There are many kinds of pipe rolling techniques and each one offers slightly different advantages and disadvantages. You will find some techniques are just a better fit for achieving the results your want. Two distinct categories exist, round and square pipe.
For instance, techniques vary for condensing coil, which is used in air conditioning units and let’s say a musical instrument like a trumpet or slide trombone. As is usually the case, each technique has advantages and disadvantages.
Form bound pipe rolling bends tubing or pipes using heat and a cylindrical, or shaped form that does not move. This process is ideal for bending pipe to an exact shape, time and time again. It’s also advantageous for smaller items that need to fit exact dimensions every time like trombones, or other musical instruments.
This technique is used to make complicated and intricate shapes. Either a press or draw tool is used to actually shape the metal in the form.
The other technique is freeform pipe rolling. In this technique a pipe is sent through a bending machine several times to achieve a certain curve. This technique is ideal for larger pieces like stair railings, or big circular bends. Trying to build a form for a long curve is just not feasible or cost-effective.
With freeform bending you can achieve any type of curve on a single machine that takes up very little shop floor space.
It has drawbacks, however. Free form bending is not as accurate, although difficult and non-geometric curves can be achieved. It also requires several run-through to get the curve right. If you have a complicated bend this technique might be too time consuming to be useful.
The Hot and Cold
Two categories reside within the above techniques. One is heat forming, the other is cold forming.
Heat might be used in form bound pipe rolling to soften metal and make is easier to bend around the form. Cold forming is also used in form bound rolling. A press typically uses no heat to bend most soft, malleable metals around a form.
Heat can also assist in free form rolling. Large diameter or thicker gage pipe is often softened with heat when rolled through a freeform press. Heavy lead or iron pipe needs some heat to bend, for instance. Many times free form rolling is cold formed, however.
Sometimes a mixture of the two is useful on complicated bends in free form rolling. Parts of a pipe are heated with a blow torch, or a heat gun before being run through a cold-press free form die. The heat is used at the discretion of the technician, and only when it does not compromise the integrity of the pipe.
These techniques offer the best, and most accurate pipe rolling for your next project.