Galling and Friction in Ironing of Thin Aluminum Cups

An experiment of ironing of aluminum cups has been carried out under various lubrication conditions. The surface appearances of the ironed cups can be classified into five main groups according to the extent of the damage caused by galling. The extent has a good positive correlation with the frictional coefficient (μ_d) at the die surface for every lubricant used on the punch side. The cup surface gradually deteriorates as the punch side friction (μ_p) increases, due to the increase in normal pressure over the die-metal interface, and vice versa. Thus it is possible to evaluate the surface appearances by means of the two frictional coefficients μ_d and μ_p. The frictional condition for a burnished smooth surface has been obtained for pure aluminum cups ironed by a tool-steel die.