Table 1 Design rules of DDI process [23, 24]

Rule 1

t₀ \(\ge\) 2 \(\times\) twall \(\times\) 1.05 (5%: Thickness reduction ratio caused by erosion

t₀: Blank thickness, twall: Liner wall thickness

Rule 2

V_b (Blank volume) = V_L (Liner volume)

Rule 3

Draw ratio in each drawing do not exceed LDR.

Rule 4

Draw ratio in 1^st deep drawing process is smaller than 2.2.

Rule 5

Draw ratio in 2^nd drawing process is smaller than 1.3 or 1.56 (1.3×1.2).

If intermediate annealing takes place after the first draw, then the values are higher by 20% (1.56).

Rule 6

Draw ratio in 3^rd drawing process is smaller than 1.2.

Rule 7

Limit reduction ratio of cross-sectional area in ironing process (LRA ironing) is 35%.

Rule 8

When ironing processes are carried out two times in one stage, each reduction ratio of the cross-sectional area (RA ironing) should be the same.

Rule 9

Limit reduction ratio of the cross-sectional area (LRA) in each stage is 50%.