Springback

Synonyms

Dimensional control; Shape distortion

Definition

Springback is generally referred to as the change of part shape that occurs upon removal of constraints after forming.

In many cases, such geometric change is undesirable as the final obtained part shape geometry deviates from the desired tooling geometry. Therefore, often people use “shape distortion” to describe springback. It is closely related to dimensional control for sheet metal parts.

Theory: Mechanics of Springback

Springback can be considered as a dimensional change which happens during unloading, due to the occurrence of primarily elastic recovery of the part. After springback the part reaches an internal equilibrium in the absence of external forces. Residual stresses still exist within the part; however, they are self-balanced. Take a simple bending case in Fig. 1, for example. Under the loaded condition of bending, the top surface is under tension, while the inner surface is under compression (Fig. 2a). During the...