A practical breakdown of the 25 fundamental stamping operations, from basic cutting to complex combined dies, with real-world application notes for toolmakers and process planners.

In everyday die design, we rarely deal with a single isolated operation. The real work starts when we combine blanking, piercing, bending, and drawing into a progressive die that runs at 60–120 SPM. The first group of core operations—blanking, piercing, trimming, and shaving—all share the same cutting mechanics, but the die clearance differs significantly. For mild steel up to 3 mm thick, we typically use 5–8% of material thickness per side for blanking, while shaving requires only 0.5–1% to achieve a clean, square edge. Many mold shops overlook the fact that a fine-blanked edge can replace a secondary machining step, cutting cycle time by 15% on average. When designing a compound die, remember that the cutting forces act simultaneously on the punch and die insert; always check the stripping force, which can be 10–20% of the total cutting force for thicker sheets.

Moving into forming operations, bending and drawing demand a different mindset—elastic recovery becomes your enemy. A 90° bend in a 2 mm thick SPCC sheet will spring back about 2–3°, so the punch angle must be compensated accordingly. For U-bending, adding a bottoming stage reduces springback variation by up to 50% compared to air bending. Deep drawing, on the other hand, is governed by the limiting drawing ratio (LDR), which for low-carbon steel is roughly 2.0 in a single draw. If your drawn cup height exceeds 0.7 times the diameter, you need a redraw operation. The blank holder force should be set at about 30% of the drawing force; too high and you tear the bottom, too low and you get wrinkles. For aluminum alloys like 5052, the LDR drops to 1.8, so plan for an extra annealing step if the part geometry demands it.

Beyond the basic 25 operations, the real productivity gains come from combining them intelligently. A typical progressive die for a bracket part might sequence: piloting, notching, bending, drawing, piercing, and final cutoff—all in one strip. The pitch accuracy must hold ±0.01 mm, which means the pilot pins must enter the strip before any forming takes place. Lubrication selection is equally critical: for high-speed blanking use low-viscosity oil (10–20 cSt), while drawing requires a chlorine-free EP additive to prevent galling. When you hit a burr problem, check the die clearance first, not the press alignment—90% of burr issues are clearance-related. For those new to combined dies, start with a simple two-operation die (blank + pierce) and measure the total force curve on a load cell; this data tells you more than any simulation. If you want to compare die designs or source specialized stamping tools, visit MoldWorld (www.moldw.com) for supplier listings and technical forums.