Springback Prediction Calculator for Stretch Forming

The Springback Prediction is a vital calculation for tooling design and dimensional accuracy in stretch forming. Our calculator helps engineers determine the Radius Increase (ΔR) that occurs when tension is released, allowing for precise die compensation. By understanding this elastic recovery, you can ensure that the Final Part Radius meets the strict tolerances required for aerospace, automotive, and high-end architectural projects.

For a complete technical assessment, you can also explore our full range of Stretch Forming Engineering Calculators to evaluate other critical factors like Bending Force and R-min.

The Challenge of Springback in Stretch Forming

Springback is the elastic recovery of a metal profile after the forming forces are removed. Because every metal has an elastic modulus, it will always attempt to return to its original shape to some degree. In stretch forming, while we significantly reduce this effect by stretching the material into the plastic range, a small, predictable increase in radius remains. Accurately predicting this recovery is essential for “Overbending”—designing the die radius slightly smaller than the target part radius to compensate for the opening of the bend.

Yield Strength: The Primary Driver of Recovery

The magnitude of springback is directly proportional to the material’s Yield Strength (σs). High-strength alloys, such as 7075-T6 aluminum, store more elastic energy during the bending process compared to softer alloys like 6061-O. When the machine releases the tension, this stored energy causes the profile to “snap back” more aggressively. Consequently, projects involving high-temper materials require more aggressive die compensation than those using annealed materials.

Geometric Factors and Die Radius (R)

The relationship between the Die Radius and the final part geometry is a critical engineering variable. Large, sweeping curves (large radii) generally experience a greater absolute increase in millimeters compared to tight, sharp bends. Furthermore, the profile’s section height and the amount of “Post-Stretch” applied by the machine can also influence the result. Increasing the post-stretch percentage can often “lock” the crystalline structure, effectively reducing the measurable springback.

Yield Strength Quick Reference (MPa)