In stamping, the die does the real work: a press applies force, but the clearance between punch and die decides whether you get a clean shear edge or a burr-ridden headache. Take Q235 cold-rolled sheet at 1.5 mm thickness. For blanking, the cutting clearance is typically set at 8%–12% of material thickness, which works out to 0.12–0.18 mm. Go tighter than that and you accelerate edge wear on the punch and die inserts; go looser and you generate burrs that cause fit-up problems in welding and assembly. In our shop, we treat that clearance window as a hard constraint, not a suggestion.

From a tooling standpoint, clearance also affects die maintenance intervals and insert material selection. For thin-gauge Q235, we usually run SKD11 or Cr12MoV inserts with a slight negative rake on the punch face to stabilize the cut. The press tonnage must be matched to both the shear strength of the material and the perimeter length of the cut. Under-tonnage leads to incomplete shearing and secondary hits; over-tonnage wastes energy and can deflect the ram. A 1.5 mm Q235 blank with a 200 mm cut perimeter typically needs roughly 12–15 tons of cutting force, so a 25-ton press gives a safe margin without beating up the tool.

Separation and forming are two sides of the same die. Once the blank is cut, bending or drawing operations demand their own clearance and radius calculations—especially when springback is a factor. The practical rule: validate clearance and tonnage on a tryout die before committing to production tooling. For more mold sourcing and stamping die supplier information, visit MoldWorld at www.moldw.com.