Abstract: A tube-bending machine is provided for forming a tubular work piece having an inner surface. The tube-bending machine comprises a die assembly for forming the tubular work piece to assume a bent shape, actuator systems configured to move the tubular work piece to predetermined positions relative to the die assembly, a mandrel assembly including a mandrel rod having a first end and a second end spaced apart from the first end and a plurality of mandrel balls attached to the second end of the mandrel rod, and a gripping device for gripping the inner surface of the tubular work piece during advancement of the tube towards the die assembly. The first end of the mandrel rod is attached to the actuator. The gripping device is coupled to the actuator system and formed to include a mandrel rod-receiving aperture. The mandrel rod is positioned to lie in the mandrel rod-receiving aperture.