Relationship between anisotropy and outer diameter change of micro metal tubes in hollow sinking

Abstract

The outer diameter of the drawn tubes of various materials was evaluated to clarify the effect of the plastic anisotropy on the outer diameter reduction in hollow sinking. Stainless steel, copper, and aluminum tubes were used as the starting materials. They were drawn for one pass by using a draw-bench machine without an inner tool. Tensile tests were conducted on the starting materials to obtain the Lankford value, which shows the plastic anisotropy. The outer diameter became smaller than the die diameter as the Lankford value increased for each drawing speed ratio. The outer diameter became smaller than the die diameter as the drawing speed ratio increased, although the Lankford value decreased. Therefore, the drawing speed ratio is more dominant for outer diameter reduction from the die than Lankford value.