springback

Springback is the elastic recovery of a material after a forming operation that has induced plastic deformation, causing the part to move toward its original shape when the loads are removed. In metal forming, springback is most noticeable in sheet metal bending, stamping, and other operations where bends or flanges do not end at the intended angle. The phenomenon occurs due to the material’s elastic rebound after unloading and the redistribution of residual stresses within the formed part.

The magnitude of springback depends on several factors. Material properties such as elastic modulus, yield strength, work hardening behavior, and anisotropy influence how much elastic recovery occurs. Process parameters including material thickness, bend radius, bend angle, and tooling geometry (die and punch radii, clearance) also play major roles, as do friction, lubrication, and temperature. Generally, sharper bends and certain materials with higher strength can exhibit more pronounced springback, and thicker sections can be more prone to it as well.

Prediction and compensation are central to managing springback. It can be measured by comparing the target geometry with the actual geometry after unloading, or estimated through finite element analysis using appropriate elastoplastic material models. To reduce springback, designers and engineers adjust tooling and process parameters, such as increasing bend radii, using multi-step or progressive bending, modifying die offsets, applying pre-stretch or springback compensation in programming, and controlling lubrication and temperature.