What Springback means
Bending is part elastic and part plastic. When the press brake releases, the elastic share recovers and the bend angle opens slightly. The amount of that recovery is springback, and it is the reason a programmed 90° bend may leave the die at 88–89° on a stiff high-strength sheet.
Why it matters on the shop floor
Springback scales with the material’s yield strength and with the inside radius to thickness ratio. Mild steel is forgiving; austenitic stainless, high-strength low-alloy steel and tempered aluminium spring back noticeably more.
In practice
In routine production the effect is absorbed by over-bending: the CNC controller commands a slightly tighter angle and the material relaxes into the target. That is why the same drawing run on two different presses, or in two different materials, can need different bending parameters — and why "the drawing says 90°" is only the start of the conversation.
What to remember
- Higher yield strength and larger R/T both increase springback.
- Coining and bottoming reduce springback by forcing more of the section into plastic deformation, at the cost of much higher tonnage.
- Where springback matters to a tolerance-critical feature, a formed-then-restruck or over-bend strategy is agreed at DFM stage rather than discovered at first article.