There are four major types of bending you could specify for your component. Today we're just looking at mandrel and rotary draw bending - go here for more information on other types.
Mandrel bending requires a rotary draw bender. The tube is bent with a mandrel inserted into the part to help keep its structural integrity. The mandrel also allows for more control to meet tighter tolerances.
Mandrel bending can be more expensive due to tooling requirements, but it's absolutely necessary for certain projects.
Related: Download Free Tube Bending Design Guide
Rotary draw bending with mandrels is the only way to achieve a high-fidelity tight radius. Without the mandrel, the tube will collapse, fracture, or ripple when bent too far. Mandrels allow easy bending up to 1-2x OD.
If your part requires little ovality and high structural integrity, mandrel bending is a must. When tubing flattens or collapses on a bend, its strength is decreased substantially.
Thin-walled tubing collapses easily when handled incorrectly. Thin walls are quick to deform and lose their shape. Mandrels provide support during the bending process for delicate tubing.
Mandrel and rotary draw bending use high-tech CNC machinery. This makes it easy to repeatedly bend complex shapes with a high degree of uniformity between parts. Specify rotary draw bending for consistent, efficient high-volume runs.
CNC machinery has evolved quite a bit with new technology. Some machines allow stacked dies or multiple bending types to be performed on a single machine. This makes multiple radii and complex shapes much easier to form.
If your part has:
Mandrel bending will produce the highest quality bent tubular component. While mandrel bending can do large bends, small runs, and simple parts, it may be more affordable to choose another bending method for those projects.
Related: 5 Ways to Control the Cost of Tube Bending Services