Influence of lubricant type on the surface quality of aluminium parts obtained by ironing

Abstract

If it is needed to achieve a higher strain rate during the ironing process, which is possible without inter-stage annealing, the ironing is performed in succession through multiple dies. During that process, changes of friction conditions occurs due to the change of contact conditions (dislodging of lubricants, changes of surface roughness, formation of friction junctions, etc.). In the multistage ironing, after each stage, the completely new conditions on the contact surfaces occur, which will significantly affect the quality of the workpiece surface. Lubricant has a very important role in ironing process of Al-alloy sheet metal: to separate the sheet metal surface from the tool and to prevent creation of adhesions on the tool, considering the high adhesive tendency of aluminum. The influence of tribological conditions in ironing process is extremely important and it was a subject of study among researches in recent years, both in the real processes and on the tribo-models. Investigation of tribological conditions in the real processes is much longer and more expensive, so testing on the tribo-models is more frequent. Experimental research on the original tribo-model presented in this paper was aimed to indicate the changes that occur during multistage ironing, as well as to consider the impact of some factors (tool material, lubricant on die and punch) on increase or decrease of the sheet metal surface roughness in ironing stages.