An ironing test of aluminum cups has been carried out under various conditions of lubrication of the punch and die. The surface appearances of the ironed cups are divided into five classes according to the intensity and the amount of the damage caused by welding, i.e. rubbed surface (bright surface), scratched surface, gouged surface, surface with microtearing and surface with micro-tearing and-cracks. The extent of the damage has a good positive correlation with the frictional coefficient μ
d on the contact surface between the die and the material for each lubricating condition on the punch. As the viscosity of the lubricant on the punch increases, indicating the decrease of μ
p, the damage is reduced. μ
p is the frictional coefficient on the punch surface. By using two parameters of μ
d and μ
p, it is possible to know what class of surface appears. A bright surface has been obtained under the condition μ
d≤-0.51μ
p+0.13.
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