In stamping, we use a press and die to force sheet or strip metal into plastic deformation or separation. On the floor, the work splits into two families: separation operations such as piercing, blanking, and cut-off, where the goal is controlled fracture along a defined contour; and forming operations such as bending, drawing, flanging, and bulging, where the material must flow plastically without cracking. From a die design standpoint, that distinction drives everything—punch and die materials, heel blocks, stripper design, and whether you need nitrogen springs or a die cushion. A separation die is basically a controlled shearing tool, so punch-to-die clearance is the single most important number on the drawing.

Take blanking as a practical example. Die clearance is normally set at 5% to 10% of sheet thickness per side. Soft materials like aluminum take the lower end, while harder grades such as stainless steel take the higher end. Get it wrong and you will see it immediately: excessive burr height, a torn fracture zone, or accelerated punch wear. In our shop, we also account for shear angle on the punch, proper die block insert fit, and adequate stripping force to prevent the strip from lifting. For forming dies, the focus shifts to bend radius, springback compensation, and draw radii that keep strain within the material's forming limit. Clearance, radius, and material condition are not suggestions—they are the difference between a stable run and a press full of scrap.

Good stamping dies rarely fail because of one big mistake; they fail from small stack-ups—clearance off by a few hundredths, a worn stripper plate, or a lubricant that does not match the alloy. Keep your clearance charts handy, verify material thickness and temper before setup, and document every die trial. For more mold sourcing and technical resources, visit MoldWorld at www.moldw.com.