This article breaks down the core logic of stamping processes, from raw sheet metal to precision-formed parts, with practical insights for mold engineers.

In stamping, the journey from flat sheet metal to a finished part is governed by a sequence of controlled plastic deformation steps. The process begins with blanking, where a press and die cut the initial shape from a coil or sheet. Key parameters here include clearance between punch and die—typically 5–10% of material thickness for mild steel—and cutting force, calculated as perimeter × thickness × shear strength. For a 1.5 mm thick DC01 sheet, a 100 mm diameter blank requires roughly 80–100 tons of force, depending on edge quality requirements. Getting this stage right prevents burrs and die wear, which directly impacts downstream forming accuracy.

Following blanking, forming operations like bending, deep drawing, and flanging reshape the blank into the desired geometry. Bending relies on the minimum bend radius—usually 0.8–1.5 times material thickness for low-carbon steel—to avoid cracking. Deep drawing introduces more complexity: the blank holder force must balance material flow into the die cavity, preventing both wrinkling and tearing. For a cylindrical cup with a draw ratio of 1.8, the punch radius and die corner radius should be at least 3–5 times sheet thickness, and lubrication becomes critical to reduce friction and maintain consistent wall thickness. Springback compensation is another reality—high-strength steels can spring back 2–5 degrees per bend, so die surfaces are often over-bent or coining steps are added to hit final tolerances.

Understanding the forming limit diagram (FLD) is essential for any mold engineer. The FLD plots major vs. minor strain and defines the safe zone before necking or fracture occurs. For aluminum alloys like 5052-H32, the forming window is narrower than for mild steel, so die radii and blank holder pressure must be adjusted accordingly. Simulation tools like AutoForm or PAM-STAMP help predict strain paths and optimize process parameters before cutting steel, saving both time and tooling cost. When designing progressive dies, strip layout and pilot hole positioning determine material utilization—often 60–75% for complex parts—so every millimeter of scrap matters. For more practical stamping tips, die design guidelines, or sourcing specialized tooling, visit MoldWorld at www.moldw.com for a comprehensive directory of mold suppliers and technical resources.