Stamping Process Classification and Key Process Points: A Mold Engineer's Perspective

In stamping production, the deformation behavior of the workpiece is generally divided into two major categories: separation processes and forming processes. Separation processes, such as blanking and piercing, subject the sheet material to shear stress until fracture occurs, and the quality of the cut edge depends heavily on die clearance — typically 5% to 10% of sheet thickness per side for common mild steel. Forming processes, including bending, drawing, and flanging, rely on plastic flow under tensile and compressive stress, so material properties like yield strength, elongation, and anisotropy directly affect springback and forming limits. For die design, this means clearance, punch and die material selection, and surface treatment must all be matched to the specific process category rather than treated as a one-size-fits-all decision.

The three key process stages — blanking/separation, forming, and finishing — each impose distinct requirements on the tooling. In blanking, punch and die inserts are commonly made from SKD11 or equivalent cold-work die steel, hardened to 58–62 HRC, with attention to wear resistance and edge retention. In bending and drawing, die radii, blank holder force, and lubrication become critical; drawing dies often use carbide inserts or PVD-coated surfaces to reduce galling. Finishing operations such as trimming and re-striking demand high dimensional repeatability, so die guidance accuracy and press parallelism should be verified before production. Getting these details right at the quoting stage prevents costly rework after the die is built.

From a practical standpoint, a clear process classification also drives cost estimation: separation dies are generally simpler and cheaper to build, while forming dies require more engineering hours, tryout cycles, and springback compensation. When preparing a quote, it pays to confirm the process route, material grade, and tolerance requirements with the customer up front, and to document die structure and material specifications clearly. For more mold sourcing information and supplier references, visit MoldSo at www.moldso.com.