The critical considerations, for our purpose, are that the bend tooling must grip the tube precisely in order to pull it around the bend this means that the tooling must be specific to the tube’s external diameter and, the central former around which the tube is drawn must match the required bend this means that the tooling must be specific to the finished tube’s bend radius. Draw Bendingĭraw bending machines can be simple NC (numerically controlled) or full CNC (computer numerically controlled). Draw bending overcomes some of the collapsing problems that can occur with compression bending.

In fact, rather than the tube being clamped behind the former it is clamped to the former and the clamp and former rotate with the tube drawn around the former in an arc behind it, just pressed to the former by a pressure die.Īs the name suggests the pressure die is not clamping the tube it is just pressing it against the former but the tube can be drawn along past it. The key difference is that the tooling pulls or draws the tube around the former tool.

Once we move to larger diameters and stiffer material, like steel, then machine power becomes essential and draw bending is the normal forming method used. Some quite elaborate shapes can be produced. To produce more complex multi-bend components, for small diameter tube where it is possible to bend it manually, hand bending jigs use compression bending. The next step up is a simple manual pipe bending tool, a type often used by plumbers for copper tube. Compression tube bendingĬompression tube bending, is akin to bending a copper pipe around your knee you are holding one end of the tube stationary and forming the tube into shape around the former (in this case your knee). There are fundamentally three approaches known respectively as compression bending, draw bending and roll bending. In order to understand the optimum design characteristics for tube bending and manipulation manufacture it is important to appreciate the different methods of tube bending.

Tube bending instructions chart