Stamping is fundamentally about applying force through a press and die to sheet, strip, tube, or profile stock so the material either plastically deforms or separates into the required shape and size. On the shop floor, the work usually falls into four categories: blanking, bending, deep drawing, and forming. The goal is simple to state and harder to execute — the material must behave: cut edges should be clean and square, bends should land at the correct angle, and material flow in drawing should be even. In blanking die design, punch-to-die clearance is typically set at 5% to 10% of sheet thickness. Softer materials call for the smaller end of that range, harder materials the larger end. Get the clearance wrong and you will see heavy burrs, excessive punch wear, or secondary shear on the fracture face.
Bending brings its own set of headaches, mainly springback. Compensation has to be built around the material's yield strength and the r/t ratio, and in practice it is rarely right the first time — expect to iterate through trial shots and adjust the die until the angle holds. Deep drawing is a different animal: the priorities shift to blank holder force and die corner radius. Too little hold-down and the flange wrinkles; too tight a radius or excessive hold-down and the cup tears at the punch nose. Lubrication and draw bead layout matter here as much as the tonnage. In all four operations, the die's guiding precision, punch-die alignment, and stripper design directly affect part consistency and die life, so clearance and fit tolerances deserve the same attention as the forming parameters themselves.
None of these numbers are universal — they are starting points that a mold engineer refines against the actual material grade, thickness tolerance, and press conditions. Recording trial results and feeding them back into the die drawing is what turns a theoretical clearance into a stable process. For more mold sourcing information and supplier resources, visit MoldSo at www.moldso.com.