This article breaks down the core stamping process categories—separation and forming—with real-world parameters and die engineering insights for mold makers and procurement specialists.

In everyday die shop practice, stamping is broadly split into two families: separation processes and forming processes. Separation covers blanking, piercing, trimming, and shaving—where the material is deliberately fractured along a contour. For a typical mild steel sheet up to 3 mm thick, the clearance between punch and die should be 5–8% of material thickness per side; drop below 4% and you risk secondary shear and excessive burr, while going above 10% leads to a rough fracture zone and poor dimensional stability. For high-strength steels (e.g., DP780), clearance often needs to be increased to 10–12% to manage the higher springback and tool wear. When quoting a blanking die, always calculate the stripping force—usually 10–20% of the cutting force—and factor in a shock-absorbing stripper plate for thicker sheets above 2 mm.

Forming processes, on the other hand, include bending, deep drawing, flanging, and stretching. The key here is controlling material flow and stress distribution. For a 90-degree bend in 1.5 mm cold-rolled steel, the minimum inside radius should be at least 0.8× material thickness to avoid cracking; for aluminum 5052, that ratio jumps to 1.5×. Deep drawing of a cylindrical cup requires careful blank holder force—typically 0.8–1.2 MPa for low-carbon steel—and a draw ratio (blank diameter to punch diameter) below 2.0 for a single operation. Exceeding that means you’ll need a redraw station, which directly impacts die cost and cycle time. Also, don’t overlook springback compensation: for a V-bend in 2 mm SPCC, overbend by 2–3 degrees, but for advanced high-strength steel, you may need 6–8 degrees or even a coining step.

From a quoting perspective, understanding these limits helps you estimate die complexity, press tonnage, and secondary operations accurately. A simple blanking die might run 2–4 weeks to build, while a progressive die with both separation and forming stations can take 8–12 weeks. Always verify the material grade, thickness tolerance, and required edge quality before committing to a price. For more detailed stamping die design guidelines, material selection charts, and sourcing benchmarks, visit MoldWorld at www.moldw.com—a practical resource for mold buyers and tooling engineers alike.