In stamping production, every operation falls into one of two categories: separation (shearing) and forming. Separation processes cut the sheet metal along a defined contour—blanking, piercing, trimming, and slitting all belong here—while forming processes change the shape of the sheet without intentionally fracturing it, covering bending, drawing, flanging, and embossing. For mold engineers, the distinction matters because the deformation mechanism drives everything downstream: punch and die clearance, material selection, tonnage requirements, and even the number of stations in a progressive die. A blanking die, for instance, typically runs with clearance at 5–10% of sheet thickness per side, whereas a drawing die needs proper blank-holder force and draw radii to control material flow and avoid tearing.
The three core operations—blanking, bending, and drawing—each impose their own design constraints. Blanking demands attention to shear angle and stripping force; a well-designed shear angle can reduce punching force by 20–30% on thick-gauge work. Bending requires accounting for springback, which for mild steel commonly runs 1–3 degrees depending on the bend radius-to-thickness ratio, so overbending or bottoming features are often built into the tool. Drawing is the most sensitive: blank-holder pressure, draw radius, and lubrication all influence whether the part forms cleanly or wrinkles and fractures. In quoting, these details translate directly into cost—a part requiring multiple drawing stages will carry a higher tooling price than a simple blank-and-pierce job.
Getting the process classification right at the quoting stage prevents unpleasant surprises later. If a RFQ involves tight tolerances on a drawn cup or a bend with a small radius relative to thickness, flag it early and budget for tryout iterations. Understanding the deformation mechanism also helps when reviewing a customer's drawing: a feature that looks like a simple bend may actually need a cam action or a secondary operation, and that changes the mold structure and price. For more mold sourcing information and supplier comparisons, visit MoldSo at www.moldso.com.