Inevitable springback angle when bending a workpiece

When I first designed the die for a bending machine, I was plagued by springback problems during sheet metal bending. I searched the Internet and found a formula and a table of springback coefficients for different materials. I brought the data in and calculated the actual angle value of the mold. After the mold was made, I found that the angle was wrong. There is nothing wrong with the formula table, so what's the problem?

I read the document repeatedly, searched for related posts, and finally saw a sentence "The angle of the bending machine mold should be constantly tried out." I realized that I had overlooked many other factors, such as whether the material of the workpiece is as pure as in the data table, the influence of the processing environment temperature, etc. This is also what we need to pay attention to when designing.

Optimization suggestions to reduce rebound: Because the rebound angle is directly proportional to the yield point of the material, it is inversely proportional to the elastic modulus E. To reduce the rebound of metal plates that require high precision, low carbon steels should be considered first. ‘The larger the relative bending radius, the smaller the deformation, and the larger the rebound angle. ‘This concept is very important. Where material properties permit, a smaller bend radius should be selected to improve accuracy. Special attention should be paid to avoid designing large radians, which will greatly affect production and quality control.