Experimental investigation of roughening of the matt surface in pack rolling

Pack rolling, wherein two stacked sheets of material are rolled at the same time, is widely used in the final pass during manufacture of aluminium foil. The resultant foil has a bright surface from the contact with the rolls and a matt surface at the interface between the two sheets. For this laboratory study, cold-rolled aluminium sheets, both with and without annealing, were subjected to pack rolling. The stacked sheets were reduced by 50% in thickness. Lubrication on the interface was varied. It is found that annealing before pack rolling leads to a significantly rougher matt surface. Lubrication on the interface does not have a strong effect on the roughening. It is also found that the topographies of the upper and lower interfaces after pack rolling are practically coincident.