So many companies claim to mandrel bend their rollbars and rollcages- whats best?
The phrase ‘mandrel bending’ is thrown around quite a bit in the aftermarket automotive world. Most rollcage materials like DOM mild steel and chromoly tubing are not suitable for mandrel bending. Even CREW tubing, which is fairly elastic, is not recommended to be mandrel bent for chassis components. When the material is formed with an internal mandrel, it takes on an enormous amount of stretching and compression. The inside wall has to compress and the outside wall has to stretch. When mandrel bending materials that are already hardened or that do not have enough elasticity, such as DOM and 4130, the work hardening that occurs in the bend area will make the component subject to failure from being pushed past its useable limits. When bending round materials for chassis and roll cage structures, the empty bending methods are much preferred over mandrel bending. Empty bending is bending without a mandrel and with specially machined tooling that incorporates a multi-radius bending die to
