Quantifying Interfacial Friction in Cold Forming using Forward Rod Backward Cup Extrusion Test

Interfacial friction plays a vital role in cold forming and forging. Since this interfacial friction, if uncontrolled, would lead to many defects and problems, it is essential to measure this entity and to overcome it. Using forward rod backward cup extrusion test, this interfacial friction is quantified. A circular billet made of aluminium alloy 6063 is extruded to form a rod on one side and a cup on the other. The ratio of the height of the cup to the rod depth is a measure of the friction. Simulations have been carried out for various combinations of height/diameter of the billet and for different punch diameter to rod diameter ratios. The cup height to rod depth ratios have been calculated for the above combinations and those ratios were plotted to form calibration curves. Subsequently, the tests have been carried out for different friction conditions applying various lubricants. By plotting the values obtained during the tests on the calibration curves, the friction present during the cold forming process is quantified.