In stamping, a press and die apply external force to sheet, strip, tube, or profile stock so the material either plastically deforms or separates into the required shape and size. For anyone working in the mold trade, this splits cleanly into two process families: separation and forming. Separation covers blanking, punching, trimming, and cut-off — the sheet fractures and separates outright. Forming covers bending, deep drawing, flanging, and bulging — the material flows plastically without fracturing. The die engineering behind each is a different animal, and that distinction drives nearly every parameter on the die drawing.
The parameters are not interchangeable, and experienced toolmakers know it. Separation dies live or die by punch-die clearance and shearing force: clearance too large produces heavy burrs and rollover, too small spikes stripping force and edge wear. Forming dies are governed instead by blankholder force, draw radius, and material flow control — set the blankholder too light in a draw and you get wrinkles, too heavy and you get tearing or a split wall. Pick the wrong parameter set for the process and the failure modes range from oversized burrs to chipped die edges and cracked punches. In practice, clearance is typically set as a percentage of sheet thickness by material — roughly 5–8% per side for mild steel, tighter for stainless and harder alloys — while blankholder force must be tuned against draw depth and blank size rather than copied from a separation job.
Good stamping die design also means matching die materials and surface treatment to the duty: separation edges benefit from wear-resistant inserts and proper heel guidance, while draw dies need polished radii and consistent lubrication to keep material flowing. Before committing to a tool, verify press tonnage against both shearing and forming loads, and confirm the die shut height and cushion capacity suit the job. Get these fundamentals right and the process runs stable; get them wrong and you will be re-cutting inserts. For more mold sourcing and supplier information, visit MoldSo at www.moldso.com.