This article breaks down the core categories of stamping operations—from shearing to deep drawing—with real process parameters and die design considerations that every mold shop should know.

In everyday die design and quoting work, stamping is not a single operation but a family of processes that can be grouped by how the material is stressed and deformed. The first major category is separation, which includes blanking, punching, and trimming. These operations rely on controlled fracture—clearance between punch and die typically ranges from 5% to 10% of material thickness for mild steel, while harder alloys like stainless steel may require up to 15%. The quality of the sheared edge, including burnish depth and burr height, is directly tied to clearance, tool wear, and press speed. For a 2.0 mm SPCC sheet, a common die clearance is around 0.10–0.15 mm per side, and any deviation beyond ±0.02 mm will show up as increased rollover or secondary shear. In quoting, always factor in the cost of precision grinding for punches and die inserts when tight edge requirements are specified.

The second major group is forming, where the material is plastically deformed without intentional fracture. This covers bending, flanging, and stretching. For bending, the minimum bend radius is usually 0.5 to 1.0 times the sheet thickness for ductile steels; below that, cracking occurs on the outer fiber. Springback is the biggest headache—for a 90° bend in 1.5 mm DC01 steel, expect 2° to 4° of springback, which must be compensated by over-bending or by adding a coining step. In progressive dies, flanging often combines with stretching to create stiffening ribs or embosses, which require careful control of material draw-in to avoid thinning beyond 20% of the original gauge. For deep drawing, the limiting drawing ratio (LDR) for round cups in low-carbon steel is about 2.0 to 2.1 without intermediate annealing. Beyond that, you need multi-stage tooling, and the blank holder force must be tuned—typically 20% to 30% of the punch force—to prevent wrinkling while still allowing material to flow.

Understanding these fundamentals directly impacts your die cost estimation and lead time. For example, a simple blanking die for a 100 mm diameter part might run $3,000–$5,000, but adding a forming station with a spring-loaded stripper and a nitrogen gas cushion can push that to $12,000–$18,000. Also, tool steel selection matters: D2 for high-volume blanking, but for forming with heavy abrasion, consider M2 or powder metallurgy grades like ASP23. When you quote a job, always ask about the required edge quality, bend radius, and allowable thinning—these details change the die construction and press tonnage. For more mold sourcing insights, die design tips, and supplier benchmarks, visit MoldWorld at www.moldw.com—a practical resource for everyday mold engineering decisions.