In stamping, every operation falls into one of two categories: separating and forming. Separating operations—blanking, piercing, trimming, and slitting—shear the sheet along a closed or open contour, and the mold designer's first concern is die clearance. As a rule of thumb, clearance runs 5–10% of sheet thickness per side for mild steel, tightened for stainless or high-strength grades to control burr height and die wear. Punch and die edges take the brunt of the load, so inserts are typically hardened to 58–62 HRC, with strippers and back-up plates sized to resist the stripping force rather than just guide the punch.

Forming operations—bending, drawing, flanging, and coining—reshape the sheet without intentionally fracturing it. Bending is governed by the minimum bend radius, commonly 0.5–1.0× material thickness for ductile steel, and by springback, which we compensate through overbend, bottoming, or a coining pass rather than trial-and-error shimming. In drawing, the draw ratio (blank diameter to punch diameter) usually stays under 2.0 for a single pass; deeper cups need redraw dies or a blank holder with controlled pressure to prevent wrinkling and thinning at the punch nose. Material grain direction matters here too—bending parallel to the rolling direction cracks far sooner than bending across it.

On the shop floor, the separating and forming stages are rarely isolated. Progressive dies combine piercing, piloting, and forming stations in one strip layout, so station pitch, pilot diameter, and scrap removal must be locked in before the die is cut. A 0.05 mm error in pilot clearance shows up as a shifted hole on every part. That is why we model the strip layout and simulate material flow before committing to steel. For more mold sourcing and technical resources, visit MoldWorld at www.moldw.com.