Nowadays bending technology plays an important role in various industries like automobile, aerospace, petroleum gas industry and other similar fields. One of the utilization of bending technology is referred as to pre-forming of tubes in the hydro forming which has increased the application of bending tubes. Various methods are applied for thin wall tube bending; among these methods; Rotary draw bending and stretch forming are more noticeable than others. In rotary draw bending, it is necessary to use essential tools such as clamp die, pressure die and bend die. Bending of tubes requires auxiliary tools like mandrel and wiper. In rotary draw bending method, tube is located between clamp die and bend die, and is bended suburb of the centre of the bend die. Pressure die prevents bending tube from moving and also it makes a higher quality of bending be preformed, which this action is known as boosting. Mandrel, as a retentive is used in the middle of the tube, which prevents of beveling in outer surface and shrinking in inner surface of the tube. Due to the high expense of the equipment; specially the mandrel, as well as the machine utilizing this method, it's currently limited to particular industries like aerospace and military ones. Different tube bending methods, how to do tube bending with rotary draw bending method, tools of this method and their influence in the tube bending process, mandrels and justify; MARGIN: 0cm 0cm 0pt; unicode-bidi: embed; DIRECTION: ltr" After introducing the chain link mandrel and its basic components, the procedure of tube bending with the aim of this mandrel was simulated using ABAQUS software and the amount of applied torques and forces were calculated. To validate the results of simulation and also verifying the quality of the bend, new mandrel is produced and practical experiments were carried out to evaluate the actual quality of the bent tubes. In addition, by using pressure gages located on the cylinder of the bending die of the system, torques and forces were obtained from practical experiments and compared with the results of the simulation. Little difference between the results proves that this new mandrel is applicable. Moreover a machine with larger size for bending of large diameter tubes is designed using forces and moments obtained from tube bending process simulation according to the available machine in industry. Key Words Tube bending, rotary draw bending, mandrel, ABAQUS, machine design.