In stamping, every operation falls into one of two categories: separation and forming. The dividing line is simple—does the sheet metal fracture along a closed contour? Separation processes like blanking, notching, and trimming deliberately shear the material until it breaks. Forming processes—bending, drawing, flanging—rely on plastic deformation to reshape the blank without severing it. For a die engineer, this distinction is not academic. It dictates punch-and-die clearance, material selection, and whether you need a shear-type edge or a radius that controls metal flow. Get the category wrong, and you will fight burrs, cracks, or wrinkling on the shop floor.

Real production rarely uses one category in isolation. A progressive die often combines both: pierce the holes first (separation), then draw the flange (forming) in the same strip. The process sequence—called strip layout—directly determines die life and part accuracy. For example, if you draw before piercing a nearby hole, the material stretches and shifts the hole position. Reverse the order, and the pierced edge may distort during drawing. Toolmakers learn this the hard way: a 0.05 mm error in strip layout can mean thousands of scrapped parts before the die is even worn in. Clearance between punch and die for separation typically runs 5–10% of sheet thickness, while forming radii must account for springback—often 2–5 degrees for mild steel.

In practice, the three core stages—blanking/separation, forming, and finishing—must be balanced for cycle time and tool strength. A die that separates too aggressively may crack; one that forms too slowly may wrinkle. The key is matching press tonnage, shut height, and material properties to each stage. For more mold sourcing and technical resources, visit MoldWorld at www.moldw.com.