Nonmandrel bending’s primary objective is to bend tubing that would normally require some form of internal support without using that support.
Nonmandrel bending saw its greatest advancement in the late 1980s and early 1990s with the completely automated computer numerical-controlled (CNC) bending machines.
he first area to consider is wall thinning. In a mandrel bend, the neutral axis is typically about one-third of the way outward of the inside radius.
The clamp die will remain unchanged from a round set of tools; that means that it will have a properly-sized round tube groove transversing the entire length.
Because the tube is being resized and reshaped during the nonmandrel bending process, tool alignment is a consideration that is just as important as it is in, for example, thin-walled tube mandrel tooling.
To use nonmandrel bending successfully, machine function and rigidity must be considered. The most widely used form of machine is the CNC rotary draw bender.
It is now time to examine how to calculate the feasibility of nonmandrel bending and apply that calculation to specific applications.
It is now possible to look a little deeper into the limits of nonmandrel bending and expose some of the possible pitfalls.