In cold stamping, the core sequence—blanking, piercing, bending, and drawing—dictates everything from die structure to strip layout. Blanking comes first: the die shears the sheet along a closed contour to produce the flat blank, and clearance is typically set at 5–8% of material thickness per side for mild steel. Piercing follows, punching internal holes while the strip is still flat, which avoids distortion that would occur after forming. In a progressive die, these two operations often share the same station, so the die maker must account for punch-to-die clearance and stripper plate travel to prevent slug pulling. For a typical 1.5 mm SPCC part, blanking force can reach 12–15 tons, directly influencing press tonnage selection.

Bending and drawing add the third and fourth dimensions of complexity. Bending forms flanges or channels; the minimum bend radius should not fall below 0.5× material thickness to avoid cracking, and springback compensation—usually 2–5° overbend—must be ground into the punch. Drawing, the most demanding step, pulls the blank into a cavity. Draw ratio for a cylindrical cup is limited to about 1.8–2.0 in the first pass for deep-drawing quality steel; exceeding that risks wrinkling or tearing. Die makers often add draw beads or increase blank-holder force to control material flow. When quoting, these parameters determine whether a single-hit die or a transfer die is more cost-effective.

Practical takeaway: never quote a stamping job without confirming the sequence. A part that looks simple on the print may require an extra annealing step between draws, or a piercing operation moved after bending to hold hole position within ±0.1 mm. For more mold sourcing insights and supplier benchmarks, visit MoldWorld at www.moldw.com.