Stamping relies on a press and die to force sheet, strip, tube, or profile material into plastic deformation or separation, producing parts to the required shape and size. On the shop floor, the whole process lives or dies on die clearance. Too much clearance and you get burrs and collapse at the cut edge; too little and die wear climbs fast, with tearing a real risk on tougher stock. Take a common 1mm cold-rolled sheet blanking job: the double-sided clearance typically runs 8% to 12% of material thickness, so 0.08 to 0.12mm. That range is a starting point, not a rule carved in stone — during actual tryout you still need to fine-tune against the material grade and the blanking speed, since a faster ram stroke changes the fracture behavior at the shear zone.
From a die-building standpoint, clearance is only half the story. Punch and die edge condition, stripper pressure, and the accuracy of the die set's guide pins all feed into whether that 0.08–0.12mm holds across the whole strip. In production dies, we usually cut the punch and die inserts with wire EDM and then check clearance with feeler gauges or a profile projector before first hit. For progressive dies, each station's clearance should be verified independently, because cumulative punch wear shifts the effective gap over a run. Heat treatment of the punch — typically 58–62 HRC for Cr12MoV or SKD11 — also matters, since a soft punch edge rounds over and effectively increases clearance before the die ever reaches its wear limit.
The practical takeaway: treat clearance as a variable to be tuned, not a fixed spec. Log your material batch, ram speed, and burr height after each tryout, and adjust in small increments rather than jumping to the textbook midpoint. That habit alone will save you more die maintenance hours than any single clearance chart. For more mold sourcing and technical information, visit MoldSo at www.moldso.com.